Linux Unix Help SHIRISH SHUKLA

Monitor Your System Performance

2011-09-07T07:26:00.000-07:00

Xxxxxxxxxxxxxxx Monitor Your System Performance xxxxxxxxxxxxxxxxxxxxX
[root@server ~]# uptime
13:14:02 up 1:30, 2 users, load average: 0.04, 0.26, 0.27

[root@server ~]# ps -eo %u | sort | uniq -c | sort -rn
56 root
22 nagios
8 apache
1 xfs

[root@server ~]# sar -c ## Process/sec
Linux 2.6.18-164.el5 (server.scratch.com) 08/24/2011
11:50:01 AM proc/s
12:00:01 PM 6.87
12:10:01 PM 6.90
12:20:01 PM 7.10
12:30:01 PM 6.77
12:40:01 PM 6.99
12:50:01 PM 6.85
01:00:01 PM 6.83
01:10:01 PM 6.92
Average: 6.90

[root@server ~]# sar -b ## Data r/wr ps
Linux 2.6.18-164.el5 (server.scratch.com) 08/24/2011
11:50:01 AM tps rtps wtps bread/s bwrtn/s
12:00:01 PM 24.81 0.18 24.63 6.37 376.94
12:10:01 PM 26.14 0.33 25.81 10.68 388.21
12:20:01 PM 57.68 28.05 29.63 620.21 466.02
12:30:01 PM 24.16 0.13 24.03 1.92 369.00
12:40:01 PM 24.55 0.10 24.44 1.70 374.73
12:50:01 PM 25.07 0.14 24.93 4.31 380.10
01:00:01 PM 24.95 0.58 24.37 6.20 377.88
01:10:01 PM 24.57 0.01 24.56 0.04 376.16
Average: 28.98 3.68 25.30 81.17 388.59

[root@server ~]# iostat -k
Linux 2.6.18-164.el5 (server.scratch.com) 08/24/2011

avg-cpu: %user %nice %system %iowait %steal %idle
0.40 0.00 3.84 0.44 0.00 95.32

Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sda 6.60 32.24 65.92 177987 363873
sda1 0.10 0.21 0.00 1163 5
sda2 6.50 32.01 65.92 176684 363868
dm-0 20.19 31.54 65.91 174109 363844
dm-1 0.02 0.08 0.00 440 0
dm-2 0.06 0.25 0.00 1397 20
dm-3 0.03 0.11 0.00 613 4

# cat /proc/stat
cpu 1864 0 16482 416939 2375 34 527 0
cpu0 1864 0 16482 416939 2375 34 527 0
intr 2416023 2368439 12 0 2 2 0 5 0 1 0 0 0 116 0 0 21 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 29989 0 0 0 0 0 0 0 37 0 0 0 0 0 0 0 17399 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ctxt 258727
btime 1314166387
processes 32539
procs_running 1
procs_blocked 0

# cat /proc/meminfo
MemTotal: 218872 kB
MemFree: 36680 kB
Buffers: 40416 kB
Cached: 79080 kB
SwapCached: 0 kB
Active: 116728 kB
Inactive: 47320 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 218872 kB
LowFree: 36680 kB
SwapTotal: 614384 kB
SwapFree: 614384 kB
Dirty: 460 kBWriteback: 0 kB
AnonPages: 44556 kB
Mapped: 15936 kB
Slab: 11628 kB
PageTables: 2320 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 723820 kB
Committed_AS: 376900 kB
VmallocTotal: 802808 kB
VmallocUsed: 3564 kB
VmallocChunk: 798832 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Hugepagesize: 4096 kB

[root@server ~]# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 23
model name : Pentium(R) Dual-Core CPU E5300 @ 2.60GHz
stepping : 10
cpu MHz : 2592.870
cache size : 2048 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss constant_tsc up pni
bogomips : 5185.74

[root@server ~]# cat /proc/buddyinfo
Node 0, zone DMA 37 33 31 29 19 12 9 2 0 0 0
Node 0, zone Normal 2217 861 467 317 71 17 6 1 1 0 0
[root@server ~]#

[root@server ~]# cat /proc/execdomains
0-0 Linux [kernel]

[root@server ~]# cat /proc/filesystems
nodev sysfs
nodev rootfs
nodev bdev
nodev proc
nodev cpuset
nodev binfmt_misc
nodev debugfs
nodev securityfs
nodev sockfs
nodev usbfs
nodev pipefs
nodev anon_inodefs
nodev futexfs
nodev tmpfs
nodev inotifyfs
nodev eventpollfs
nodev devpts
ext2
nodev ramfs
nodev hugetlbfs
iso9660
nodev mqueue
ext3

[root@server ~]# cat /proc/loadavg
0.33 0.36 0.29 1/92 2916

[root@server ~]# cat /proc/locks
1: POSIX ADVISORY READ 2689 fd:00:320039 4 4
2: POSIX ADVISORY WRITE 2732 fd:00:931460 0 EOF
3: POSIX ADVISORY READ 2689 fd:00:320021 4 4

[root@server ~]# cat /proc/net/tcp
sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 00000000:0185 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 7642 1 c8adbb40 3000 0 0 2 -1
1: 0100007F:0CEA 00000000:0000 0A 00000000:00000000 00:00000000 00000000 27 0 7887 1 c8adb240 3000 0 0 2 -1
2: 00000000:008B 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 8138 1 c8ada4c0 3000 0 0 2 -1
3: 00000000:006F 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 7482 1 c9720040 3000 0 0 2 -1
4: 00000000:0015 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 7778 1 c8adb6c0 3000 0 0 2 -1

[root@server ~]# cat /proc/net/udp
sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
9: 0A08A8C0:0089 00000000:0000 07 00000000:00000000 00:00000000 00000000 0 0 8108 2 c4db8d00
9: 0908A8C0:0089 00000000:0000 07 00000000:00000000 00:00000000 00000000 0 0 8106 2 c4db32c0
9: 0808A8C0:0089 00000000:0000 07 00000000:00000000 00:00000000 00000000 0 0 8104 2 c4db36c0
9: 0708A8C0:0089 00000000:0000 07 00000000:00000000 00:00000000 00000000 0 0 8102 2 c4db3ac0
9: 00000000:0089 00000000:0000 07 00000000:00000000 00:00000000 00000000 0 0 8099 2 c8a04080
[root@server ~]# cat /proc/net/protocols
protocol size sockets memory press maxhdr slab module cl co di ac io in de sh ss gs se re sp bi br ha uh gp em
RAWv6 648 -1 -1 NI 0 yes ipv6 y y y n y y y n y y y y n y y y y n n
UDPv6 620 -1 0 NI 0 yes ipv6 y y y n y n y n y y y y n n y y y y n
TCPv6 1248 19 1 no 224 yes ipv6 y y y y y y y y y y y y n n y y y y y
PACKET 444 -1 -1 NI 0 no kernel n n n n n n n n n n n n n n n n n n n
UNIX 416 -1 -1 NI 0 yes kernel n n n n n n n n n n n n n n n n n n n
RAW 500 -1 -1 NI 0 yes kernel y y y n y y n n y y y y n y y y y n n
UDP 508 -1 0 NI 0 yes kernel y y y n y n y n y y y y y n y y y y n
TCP 1136 19 1 no 224 yes kernel y y y y y y y y y y y y n n y y y y y
NETLINK 404 -1 -1 NI 0 no kernel n n n n n n n n n n n n n n n n n n n

[root@server ~]# cat /proc/partitions
major minor #blocks name
8 0 31457280 sda
8 1 104391 sda1
8 2 20860402 sda2
253 0 7168000 dm-0
253 1 512000 dm-1
253 2 3891200 dm-2
253 3 2048000 dm-3

[root@server ~]# cat /proc/schedstat
version 12
timestamp 2436227
cpu0 4336 4336 7 4343 7528 307075 58464 139144 139144 192048 1771799 248611
domain0 00000001 661081 661081 0 0 0 0 0 661081 360 360 0 0 0 0 0 360 58464 58464 0 0 0 0 0 58464 0 0 0 0 0 0 0 0 0 0 0 0

[root@server ~]# cat /proc/stat
cpu 2085 0 18967 484888 2403 42 607 0
cpu0 2085 0 18967 484888 2403 42 607 0
intr 2808623 2749553 12 0 2 2 0 5 0 1 0 0 0 116 0 0 21 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 33013 0 0 0 0 0 0 0 37 0 0 0 0 0 0 0 25861 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ctxt 302029
btime 1314166387
processes 37438
procs_running 1
procs_blocked 0

[root@server ~]# cat /proc/swaps
Filename Type Size Used Priority
/dev/mapper/MYVOL-SWAPer partition 511992 0 -1
/extraswap file 102392 0 -2

[root@server ~]# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: VMware, Model: VMware Virtual S Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02
[root@server ~]# cat /proc/tty/drivers
/dev/tty /dev/tty 5 0 system:/dev/tty
/dev/console /dev/console 5 1 system:console
/dev/ptmx /dev/ptmx 5 2 system
/dev/vc/0 /dev/vc/0 4 0 system:vtmaster
serial /dev/ttyS 4 64-95 serial
pty_slave /dev/pts 136 0-1048575 pty:slave
pty_master /dev/ptm 128 0-1048575 pty:master
unknown /dev/tty 4 1-63 console

[root@server ~]# cat /proc/uptime
5253.31 4967.57

[root@server ~]# cat /proc/version
Linux version 2.6.18-164.el5 (mockbuild@builder16.centos.org) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-46)) #1 SMP Thu Sep 3 03:33:56 EDT 2009

Other that are usefulls :
[root@server ~]# cat /proc/interrupts
[root@server ~]# cat /proc/iomem
[root@server ~]# cat /proc/vmstat
[root@server ~]# vmstat -m

## Check NC status
[root@server ~]# mii-tool eth0

--Shirish Shukla

IMP Linux Services

2011-05-14T22:57:00.000-07:00

xxxxxxxxxxxxx Important Linux Services in Linux and there meanings xxxxxxxxxxxxx

# chkconfig sshd --list                    [To check daemon default on boot running status ]
# service daemon-name status      [Check daemon present status ]
# service --status-all     [Check all running service ]
# ntsysv                                            [Change services status ]

gpm	needed if you want to use the mouse at the console
kudzu	important for detecting new hardware
syslog	important for syslog services
netfs	needed only if there are NFS shares that should be mounted at boot time
network	important for starting network interfaces (e.g. eth eth1bonding...)
random	used for the system entropy pool
atd	needed if the at(1) service is used instead of cron
apmd	Advanced Power Management (APM) daemon is used for laptops and some desktops
isdn	needed if ISDN is being used
iptables	needed if Netfilter (iptables) Firewall is being used
ip6tables	needed if ip6tables Firewall is being used
pcmcia	not needed on servers - needed for laptops
irqbalance	important for distributing interrupts across all CPUs
sendmai	needed if Sendmail is used - Procmail should be used which is more secure
autofs	needed if automounter is used - production applications should not be dependent on automounter
sshd	important for logins via SSH
portmap	needed if e.g. NFS is being used
nfslock	needed if NFS shares are mounted
nfs	needed if server runs the NFS server
mdmonitor	needed only if software RAID is being used
crond	important for running cron jobs
xinetd	needed if xinetd services are being used see /etc/xinetd.d/ for list of services
cups	needed if CUPS is used for the printing system
rhnsd	needed if server should connect to RHN to check for software updates etc.
sysstat	needed to reset system statistics logs
audit	needed only if Linux Audit Subsystem (LAuS) should run for collecting system call audit records
psacct	needed only if kernel process accounting information is needed
smartd	important for monitoring disk problems if hard disks support SMART technology
netdump	important if kernel oops data and memory dumps should be sent to a Netdump server for server crashes

Rest will add sooooonnnn .....

Diff ext2 ext3 ext4

2011-05-14T22:24:00.000-07:00

xxxxxxxxxxxxxxxxxxxxx Diff ext2 ext3 ext4 xxxxxxxxxxxxxxxxxxxxxxxxx

Extended n file system

ext2 :
- Introduced with kernel 1.0 in 1993
- Flexible can handle upto 4TB
- Support file-name upto 1012 chars
- super block feature increase file system performance
- ext2 reserve 5% of disk space for root
- ext2 is popular on USB and other solid-state devices.
This is because it does not have a journaling function.
so it generally makes fewer reads and writes to the drive,
effectively extending the life of the device .
- NO journalalizm

ext3 :
- Provide all the feature of ext 2 + journaling and backward compatibility .
- can upgrade ext2 to ext3 without loss of data.
- journaling feature speed up the system to recover the state after power-failure
or improper mount unmount etc.
- Example: In ext2 in an improper unmount or in-between power-off etc.. so in time
of receiver it checks whole file system .
But in ext3 it keeps record of uncommitted file transactions and checks applied
on on them so system will come back up in faster and quicker .
-

ext4:
- Introduced with kernel 2.6.28
- Ext4 is a deeper improvement over Ext3
- support larger filesystem, faster checking, nanosecond timestamps,
and verification of the journal through checksums.
- It’s backward and forward compatible with versions 2 and 3, so we can
mount a ext2 or ext3 filesystem as ext4 .
- The main benefits that ext4 has over ext3 are:
- faster time-stamping
- faster file system checking
- journaling check-sums
- extents (basically automatic space allocation to avoid fragmentation)

What is Journalism in linxu file syatem ?
A journaling file system is a file system that keeps track of the changes that will be made in
a journal (usually a circular log in a dedicated area of the file system) before committing them to
the main file system. In the event of a system crash or power failure, such file systems are quicker
to bring back online and less likely to become corrupted.

File Permission Linux

2011-05-14T22:21:00.000-07:00

xxxxxxxxxxxxxxxxxxxxxx File Permission xxxxxxxxxxxxxxxxxx

Set user ID, set group ID, sticky bit

- SUID or setuid: Change user ID on execution. If setuid bit is set, when the file will be executed by a user,   the process will have the same rights as the owner of the file being executed.
- SGID or setgid: Change group ID on execution. Same as above, but inherits rights of the group of the owner of the file on execution. For directories it also may mean that when a new file is created in the directory it will inherit the group of the directory (and not of the user who created the file).
- Sticky bit: It was used to trigger process to "stick" in memory after it is finished, now this usage is obsolete. Currently its use is system dependant and it is mostly used to suppress deletion of the files that belong to other users in the folder where you have "write" access to.
               -->> If the sticky bit is set for a directory, only the owner of that directory or the owner of a file can delete or rename a file within that directory.

               EG: Login as root
                                     # mkdir /usr/Shirish
                                     # touch /usr/Shirish/shukla
                                     # chmod -R 1777 /usr/Shirish/shukla
                      Login as normal user : sks
                                     # ls -l /usr/Shirish/shukla
                                        -rwxrwxrwt 1 root root 16 Feb 11 00:31 /usr/Shirish/shukla
                                     # rm -fr /usr/Shirish/shukla
                                        rm: cannot remove `/usr/Shirish/shukla': Operation not permitted


SUID bit is set for files ( mainly for scripts ).
The SUID permission makes a script to run as the user who is the owner of the script, rather than the user who started it.

SGID, it will run with the privileges of the files group owner, instead of the privileges of the person running the program.

-----------------------------------------------------------------------------------
0755 -> setuid, setgid, sticky bits are cleared        000
1755 -> sticky bit is set                                            001
2755 -> setgid bit is set                                       010
3755 -> setgid and sticky bits are set                      011
4755 -> setuid bit is set                                           100
5755 -> setuid and sticky bits are set                      101
6755 -> setuid and setgid bits are set                     110
7755 -> setuid, setgid, sticky bits are set              111
-----------------------------------------------------------------------------------

Types of Processes in linux

2011-05-03T21:05:00.000-07:00

xxxxxxxxxxxxxxxxxx Types of Process in Linux xxxxxxxxxxxxxxxxxxxxxxxx

Every application it may be system specific or application daemon specific. It have to started as process
in background or foreground as designed.

Below are the few common process states:

Runnable: Process started and it's running and is in active queue in meantime it may in waiting for CPU resource.

Stopped: Process started and stopped in between but is not fully killed and can run if started again.

Sleeping/Waiting: Process started and at meantime there are to many request to CPU from some other process or it's is waiting for another process to complete.

Zombie: Process started and started another child process and then parent process gone/died, in such condition that child process doesn't know how to end, so it's hang around but living, such process is known as zombie process.

More About Foreground/Background Process < fg and bg command linux >

how a normal user update shadow file on password change

2011-04-29T04:21:00.000-07:00

xxxxxxxxxxx How a normal user changes his password and updated shadow file xxxxxxxxxxxxx

Note:
permission on /etc/shadow is: 400
permission on /etc/password : 644
permission on /usr/bin/passwd : 4755 ( suid is set)

Can root change own/others password ?: yes (Even he is having read permission on shadow,
but ofcourse root can update any file which is on properly mounted partition)

But can a normal user change his pasword ? : Yes (HOW? he is not having write permission on password and even not having read permission on shadow so how????)

Here's the solution why??

# which passwd
/usr/bin/passwd

# ls -l /usr/bin/passwd
-rwsr-xr-x 1 root root 27768 Jan 6 2007 /usr/bin/passwd

Note: The permission on command binary /usr/bin/passwd is 4755 mean any user can execute it and suid is set on it mean, it must be executed as root it's dose not matter who is executing it, and root have authority to update any file .

But if we look into this scenario then can user keep any password of him and can he change any's password Noooo???

Because passwd binary it's itself authenticate via PAM and run accordingly.

=> inode is is data structure in unix/linux file system

ssh without password

2011-04-21T07:13:00.000-07:00

xxxxxxxxxxxxxxxxxxxxx SSH Login Without Password By- Shirish Shukla xxxxxxxxxxxxxxxxxxxxxxx

Example: ssh from shirish@client-1 to shukla@server-1 without password
Server-1: 192.168.8.10
Client-1: 192.168.8.20

#####ON Client-1: 192.168.8.20 : user shirish
### Login as shirish

# ssh-keygen -t dsa
----------------------------------------------->> Just press Enter don't type anything

Generating public/private dsa key pair.
Enter file in which to save the key (/home/shirish/.ssh/id_dsa): <--Enter
Created directory '/home/shirish/.ssh'.
Enter passphrase (empty for no passphrase):                          <--Enter
Enter same passphrase again:                                               <--Enter
Your identification has been saved in /home/shirish/.ssh/id_dsa.
Your public key has been saved in /home/shirish/.ssh/id_dsa.pub.
The key fingerprint is:
d8:6c:cb:2a:e7:24:01:43:9f:96:4a:45:e6:93:9b:f4 shirish@my.scratch.com

# ssh-copy-id -i .ssh/id_dsa.pub shukla@192.168.8.10

The authenticity of host '192.168.8.10 (192.168.8.10)' can't be established.
RSA key fingerprint is e8:0b:8a:d3:1a:d1:ce:ec:d8:f9:13:31:79:c8:03:ed.
Are you sure you want to continue connecting (yes/no)? yes                        <--type yes
Warning: Permanently added '192.168.8.10' (RSA) to the list of known hosts.

Password:                                <-- type password of shukla on Server-1: 192.168.8.10

Now try logging into the machine, with "ssh 'shukla@192.168.8.10'", and check in:

.ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

#####ON Server-1: 192.168.8.10
### Login as shukla and confirm following
1> permission of /home/shukla/.ssh    700
$ ls -lrthd .ssh/
drwx------ 2 shukla shukla 4.0K Mar 12 13:51 .ssh/

2> permission of /home/shukla/.ssh/authorized_keys    600
$ ls -lrth .ssh/
-rw------- 1 shukla shukla 614 Mar 12 13:51 authorized_keys

########### Now login as shirish on Client-1:192.168.8.20
## ssh shukla@192.168.8.10
------------------------------------------------------>> It will not prompt for password

# Faced any problem Feedback in above contact me
#===============================Scratch=============================#
# AND Many More .....................Linux is Endless                       #
#=========================== Hope you Liked IT ========================#
#                                           SSH-I -- BY Shirish Shukla   #
#                                                   RHC Engineer 2010 #
#                                              shirish.linux@gmail.com #
#                                               shirishlinux.blogspot.com #
#    "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#=================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk      #
#=================================================================#

Script to take MBR backup

2011-03-23T09:41:00.005-07:00

xxxxxxxxxxxx BASH To Take MBR BAckup -- Shirish Shukla xxxxxxxxxxxxx

#!/bin/bash

hdds=$(echo /dev/[hs]d?)

for hdd in $hdds

## take only last name of dir

base=$(basename $hdd)

##take MBR Backup 0-512 bytes

dd if=$hdd of=/tmp/$base.mbr count=1 bs=512

echo $hdd

done

Install Configure Nagios

2011-03-16T07:58:00.000-07:00

xxxxxxxxxx Install & Manage NAGIOS Monitoring tool by Shirish Shukla xxxxxxxxxxxxx

Nagios® is a system and network monitoring application. (Description from some source)
Some of the many features of Nagios® include:
- Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.)
- Monitoring of host resources (processor load, disk usage, etc.)
- Simple plugin design that allows users to easily develop their own service checks
- Parallelized service checks
- Ability to define network host hierarchy using "parent" hosts, allowing detection of and     distinction between hosts that are down and those that are unreachable
- Contact notifications when service or host problems occur and get resolved (via email, pager,   or user-defined method)
- Ability to define event handlers to be run during service or host events for proactive          problem resolution
- Automatic log file rotation
- Support for implementing redundant monitoring hosts
- Optional web interface for viewing current network status, notification and problem history,   log file, etc.

PREREQUISITE:
=============
Apache (https)
gcc libraries

Nagios Tols:
============
# mkdir /root/SW
wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.3.tar.gz
wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.11.tar.gz

##Adduser and groups

# useradd -m nagios
# passwd nagios

# groupadd nagios              <--Just for confirmation
# usermod -G nagios nagios     <--Just for confirmation

# groupadd nagcmd
# usermod -a -G nagcmd nagios
# usermod -a -G nagcmd wwwrun <--Not Require(optional) need to create group wwwrun before

INSTALLATION:
=============
# cd /root/SW
# tar xzf nagios-3.2.3.tar.gz
# cd nagios-3.2.3

# ./configure --with-command-group=nagcmd
# make all
# make install
# make install-init
# make install-config
# make install-commandmode

# vi /usr/local/nagios/etc/objects/contacts.cfg
At line
35: Change --> email           youadmin-mail-id

# make install-webconf
# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Note: if you want to change admin "nagiosadmin" name chanhe all in "/usr/local/nagios/etc/cgi.cfg" file too .

##Start httpd(Apache)
# /etc/init.d/httpd restart
# chkconfig httpd on

### Instal nagios-plugin
# tar xzf nagios-plugins-1.4.11.tar.gz
# cd nagios-plugins-1.4.11
# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
# make
# make install

#### Start nagios
# /etc/init.d/nagios restart
# chkconfig nagios on

###### How to OPERATE

# Webadmin panel
http://your-ip/nagios/ < Provide above seted id & password---

EG: To Check All Hosts without options You can set it to your default apache hosting file for your monitoring purpose
http://192.168.8.10/nagios/cgi-bin/status.cgi?host=all

### Want default as above to your ip
# vi /var/www/html/index.html
<html>
<head>
<META HTTP-EQUIV="Refresh"
CONTENT="2; URL=http://192.168.8.10/nagios/cgi-bin/status.cgi?host=all">
</head>
<body bgcolor="pink">
<br />
<br />
<br />
<br />
<br />
<br />
<Center>
<h1> <font color="green"> Wait 2 Sec.............</font></h1>
</body>
</html>

##Save and relaod httpd

Now just type your ip on browser and <---Enter

####################################################
#################Add your servers to monitor ############
###################################################
# cd /usr/local/nagios    <-- Nagios default files

# cd /usr/local/nagios/etc/objects <<-- All cfg file server's config file to monitor

# cat /usr/local/nagios/etc/nagios.cfg <<<-- NAgios main config file

# vi /usr/local/nagios/etc/nagios.cfg <<<--Add your own config dirs where your all server cfg file will reside

==>Add below line

cfg_dir=/usr/local/nagios/etc/lnx-servers

# cd usr/local/nagios/etc/lnx-servers

# vi my-samba_server

##############################################################
############# HOST DEFINITION ###############################
##############################################################
# HOST DEFINITION
   define host{
        use                     linux-server            ; defined in template
        host_name               scratch-samba.8.10
        alias                   samba-server
        address                 192.168.8.10
        }

# HOST GROUP DEFINITION (Optional, you can add multiple members to your already created group seperated by comma)
define hostgroup{
        hostgroup_name my-servers             ; The name of the hostgroup
        alias           MY Linux Servers         ; Long name of the group
        members         scratch-samba.8.10      ; Comma separated list of hosts that belong to this group
       }

##############################################################
####################### SERVICE DEFINITIONS #################
##############################################################

###Ping check
define service{
        use                             local-service                 ; defined in template /usr/local/nagios/etc/objects/templates.cfg
        host_name                       scratch-samba.8.10
        service_description             PING
        check_command                   check_ping!100.0,20%!500.0,60% ; Defined in commnd file /usr/local/nagios/etc/objects/commands.cfg
        }

### SSH service Check
define service{
        use                             local-service
        host_name                       scratch-samba.8.10
        service_description             SSH
        check_command                   check_ssh!-t 5 -r "OpenSSH_4.2"
        }

define service{
        use                             local-service         ; Name of service template to use
        host_name                       scratch-samba.8.10
        service_description             samba
        check_command                   check_http
        }

define service{

        use                     local-service           ; Inherit default values from a template
        host_name               scratch-samba.8.10
        service_description     SMTP
        check_command           check_smtp
        }

#check port 139
define service{
        use                     local-service           ; Inherit default values from a template
        host_name               scratch-samba.8.10
        service_description     Samba_port139
        check_command           check_tcp!139
        }

##########################################################################

## Nagios Fine tunning file (Do not replace original line comment that then add below line)
# vi /usr/local/nagios/etc/cgi.cfg

### Don't show pending satate of service
use_pending_states=0

### Disable webadmin auth
use_authentication=0

### Want to authorize an user shukla to have all admin rights for weadmin panel
authorized_for_system_information=shukla
authorized_for_configuration_information=shukla
authorized_for_system_commands=shukla
authorized_for_all_hosts=shukla
authorized_for_all_services=shukla
authorized_for_all_service_commands=shukla
authorized_for_all_host_commands=shukla

### Want default guest user, WARN: dont' allow this
default_user_name=guest

### Want an read only user
#htpasswd -c /usr/local/nagios/etc/htpasswd.users user1
#using command add more users
authorized_for_read_only=user1

### Want to change ping syntax
ping_syntax=/bin/ping -n -U -c 5 $HOSTADDRESS$

### Refresh rate of cgi (status, statusmap, extinfo, and outages) in sec
refresh_rate=60

### Want to play sound on webpanel if error occour on network
## Plcace your audio file at
# /usr/local/nagios/share/media
##Un commen tbelow lines after adding resp audio files
#host_unreachable_sound=hostdown.wav
#host_down_sound=hostdown.wav
#service_critical_sound=critical.wav
#service_warning_sound=warning.wav
#service_unknown_sound=warning.wav
#normal_sound=noproblem.wav

### dont allow to change author name while submitting comment
lock_author_names=0

# vi /usr/local/nagios/etc/nagios.cfg

### Change log path
log_file=/usr/local/nagios/var/nagios.log

## Add your specific cfg file of server to monitor
cfg_file=/usr/local/nagios/etc/objects/myserver.cfg

## Add you dir contain your server cdf file to monitor all
cfg_dir=/usr/local/nagios/etc/my-lnx-servers

## Host update interval in sec
status_update_interval=5

## Change nagios user & Group (NOT Recomended)
nagios_user=nagios
nagios_group=nagios

## Add you own command file
check_external_commands=0
command_check_interval=-1
command_file=/usr/local/nagios/var/rw/nagios.cmd <<--As you want
external_command_buffer_slots=4096

## Nagios store his pid at
lock_file=/usr/local/nagios/var/nagios.lock

##### agios Log rotation
#       n       = None - don't rotate the log
#       h       = Hourly rotation (top of the hour)
#       d       = Daily rotation (midnight every day)
#       w       = Weekly rotation (midnight on Saturday evening)
#       m       = Monthly rotation (midnight last day of month)

log_rotation_method=d
log_archive_path=/usr/local/nagios/var/archives

##Use syslog to do so
use_syslog=1

##### MAXIMUM SERVICE CHECK SPREAD in munute
max_service_check_spread=30

### HOST FRESHNESS CHECK OPTION (Nagios chek periodically freshmess of hosts)
check_host_freshness=1
host_freshness_check_interval=20

### Change date format
#       us              (MM-DD-YYYY HH:MM:SS)
#       euro            (DD-MM-YYYY HH:MM:SS)
#       iso8601         (YYYY-MM-DD HH:MM:SS)
#       strict-iso8601 (YYYY-MM-DDTHH:MM:SS)
date_format=us

##Enable perl support
##not in use if u have not compliled nagios with perl
p1_file=/usr/local/nagios/bin/p1.pl
###disable =0
enable_embedded_perl=1

# ADMINISTRATOR EMAIL/PAGER ADDRESSES
admin_email=nagios@localhost

# DEBUG LEVEL
#          -1 = Everything
#          0 = Nothing
#          1 = Functions
#          2 = Configuration
#          4 = Process information
#          8 = Scheduled events
#          16 = Host/service checks
#          32 = Notifications
#          64 = Event broker
#          128 = External commands
#          256 = Commands
#          512 = Scheduled downtime
#          1024 = Comments

debug_level=0

# DEBUG VERBOSITY
# Values: 0 = Brief output
#         1 = More detailed
#         2 = Very detailed

debug_verbosity=1

# DEBUG FILE
debug_file=/usr/local/nagios/var/nagios.debug

############################ BASIC Checking #############################

### Check Your Config files for error

# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
# /etc/init.d/nagios start

########## Tunnning

1> Want any new updates to be check every minute (Default 5 minute)
# vi /usr/local/nagios/etc/objects/templates.cfg

check_interval      1 ; Actively check the host every 1 minutes

2> I want to check default ping of my server
check_command                   check-ping

3> I want to use all config waht i defined in my template linux-server to windows-server
Add below line in windows.cfg
use linux-server

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
# AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ========================#
#                                         NAGIOS -- BY Shirish Shukla #
#                                                   RHC Engineer 2010 #
#                                             shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
# "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#=====================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=====================================================================#

mysql master -slave Replication

2011-03-16T07:38:00.000-07:00

..........mysql master slave replication configuration on LINUX.......- Shirish Shukla

Some Basics:
Port No: 3306 (TCP/UDP)

IPADDRESS_Set as per your requirement

SYATEM 1 >> master   : 192.168.8.10
SYATEM 2 >> Slave    : 192.168.8.20

1> Installation on both server

# yum install mysql*

# /etc/init.d/mysqld restart
# /etc/init.d/mysqld restart

                                                      ### Set root password
# mysqladmin -u root password x                       ### replace x is ur password

Login in mysql:

# mysql -u root -px                                   ### replace x is as ur password aviod direct
                                                      ### passing of password for security reason
# mysql -u root -p     <Enter>
Enter password:    <Enter Password>
mysql> exit

2> ON MASTER--192.168.8.10

# cp /etc/my.cfg /etc/my.cfg_Org                      ### Keep a copy
# vi /etc/my.cnf

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
###Default to using old password format for compatibility with mysql 3.x
### clients (those using the mysqlclient10 compatibility package).
old_passwords=1

server-id=1
binlog-do-db=SHUKLA               ### databases which you want to replicate
binlog-do-db=SHIRISH                # create these databases before SEE
                                    # at END BASIC MYSQL COMMANDS
                                    # use, to add in 1 line or add seperately
binlog-ignore-db=mysql            ### Input the database that should be ignored
binlog-ignore-db=test               # for replication

log-bin=/var/lib/mysql/mysqld-bin

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
relay-log=/var/log/mysql-relay-bin

# mysql -u root -p

mysql> grant replication slave on *.* to replication@192.168.8.20 identified by 'slave';
mysql> GRANT ALL PRIVILEGES ON *.* TO replication;

Cross check user replication
======================
mysql> use mysql;
mysql> select * from user where User='replication';        ### must show 'Y' in most fields specially in "Super_priv"

#### Now Craete some database and tables

mysql> CREATE DATABASE SHIRISH;
mysql> use SHIRISH;
mysql> create table members(name char(20), age varchar(20));
mysql> show tables;
mysql> insert into members(name, age) values ('Shirish Shukla', 23);
mysql> insert into members(name, age) values ('Shirish Shukla-2', 23);
mysql> insert into members(name, age) values ('Shirish Shukla-3', 23);
mysql> select * from members;
+------------------+------+
| name             | age |
+------------------+------+
| Shirish Shukla | 23   |
| Shirish Shukla-2 | 23   |
| Shirish Shukla-3 | 23   |
+------------------+------+
3 rows in set (0.00 sec)

mysql> exit

3> ON SLAVE--192.168.8.20
# cp /etc/my.cfg /etc/my.cfg_Org               ### Keep a copy
# vi /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1

server-id=2
master-host = 192.168.8.10
master-user = replication
master-password = slave
master-port = 3306
log-bin=/var/lib/mysql/mysqld-bin

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
relay-log=/var/log/mysql-relay-bin

# mysql -u root -p

mysql> stop slave;
mysql> CHANGE MASTER TO MASTER_HOST='192.168.8.10',MASTER_USER='replication',MASTER_PASSWORD='slave';
mysql> GRANT ALL PRIVILEGES on *.* TO replication

Cross check user replication
======================
mysql> use mysql;
mysql> select * from user where User='replication';        ### must show 'Y' in most fields specially in "Super_priv"

mysql> start slave;
mysql> show slave status\G;
*************************** 1. row ***************************
             Slave_IO_State: Waiting for master to send event            <1>
                Master_Host: 192.168.8.10                                 <2>
                Master_User: replication                                  <3>
                Master_Port: 3306                                         <4>
              Connect_Retry: 60
            Master_Log_File: mysqld-bin.000008                            <5>
        Read_Master_Log_Pos: 223                                          <6>
             Relay_Log_File: mysqld-relay-bin.000002
              Relay_Log_Pos: 361
      Relay_Master_Log_File: mysqld-bin.000008
           Slave_IO_Running: Yes                                          <7>
          Slave_SQL_Running: Yes                                          <8>
            Replicate_Do_DB:
        Replicate_Ignore_DB:
         Replicate_Do_Table:
     Replicate_Ignore_Table:
    Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
                 Last_Errno: 0
                 Last_Error:
               Skip_Counter: 0
        Exec_Master_Log_Pos: 223                                          <9>
            Relay_Log_Space: 361
            Until_Condition: None
             Until_Log_File:
              Until_Log_Pos: 0
         Master_SSL_Allowed: No
         Master_SSL_CA_File:
         Master_SSL_CA_Path:
            Master_SSL_Cert:
          Master_SSL_Cipher:
             Master_SSL_Key:
      Seconds_Behind_Master: 0                                           <10>
1 row in set (0.01 sec)

ERROR:
No query specified

#### CROSS check some things in above;
<1>Always "Waiting for master to send event" if unable to connect then report or restrat
<2>Muyst show master IP
<3>Show user as set above
<4>PORT 3306
<5>must match with below (show master status;) FILE
<6>must match with below (show master status;) Position
        On master RUN
        mysql> show master status;
+-------------------+-----------+-------------------------------+------------------------+
| File              | Position | Binlog_Do_DB                  | Binlog_Ignore_DB      |
+-------------------+-----------+-------------------------------+------------------------+
| mysqld-bin.000008 |      223 | SHUKLA,SHIRISH,SHUKLA,SHIRISH | mysql,test,mysql,test |
+-------------------+-----------+-------------------------------+------------------------+

<7>Must show Yes
<8>Must show Yes
<9> SAME As <6>
<10>Must show limited sec diff < 2 or 0 sec but not 'NULL'

3> TESTING MASTER SLAVE
#### Now cross check is replacition done properly or not !!!

mysql> show databases;
mysql> use SHIRISH;
mysql> show tables;       <--- Compare with master
mysql> select * from members; <--- Compare with master

### Now create a new table as LINUX at MASTER;

mysql> SHOW TABLES;
mysql> create table linux(name char(20), age varchar(20));
mysql> insert into linux(name, age) values ('Shirish Shukla', 23);
mysql> SHOW TABLES;
+--------------------------+
| Tables_in_SHIRISH       |
+--------------------------+
| linux                   |
| members                 |
+--------------------------+
2 rows in set (0.00 sec)

## now at slave

mysql> use SHIRISH;
mysql> show tables;
mysql> select * from linux;    << MUST SHOW SAME AS MASTER JUST UPDATED>>

Some Tuning.....add below in /etc/my.conf of both master and slave........

==========================================================================
||                    MASTER SLAVE <--> MASTER SLAVE                    ||
==========================================================================

Continue above configuration and add BELOW....

                     192.168.8.10      192.168.8.20
                       SYSTEM-1          SYSTEM-2
Now Above AS:          Master <------> SLAVE
                       SLAVE   <------> MASTER2

ON SYSTEM-1
# vi /etc/my.cnf    <<--Add below lines

master-host = 192.168.8.20
master-user = replication
master-password = slave
master-port = 3306

# /etc/init.d/mysqld restart

# mysql -u root -px
mysql> stop slave;
mysql> grant replication slave on *.* TO ayam@'192.168.8.10' identified by 'x';
mysql> grant replication slave on *.* TO ayam@'192.168.8.20' identified by 'x';
mysql> GRANT ALL PRIVILEGES ON *.* TO replication@192.168.8.10;
mysql> GRANT ALL PRIVILEGES ON *.* TO replication@192.168.8.20;
mysql> GRANT ALL PRIVILEGES ON *.* TO replication;
mysql> CHANGE MASTER TO MASTER_HOST='192.168.8.20',MASTER_USER='replication',MASTER_PASSWORD='slave';
mysql> start slave;

ON SYSTEM-2
# vi /etc/my.cnf    <<--confirm below line we had already added in Part -1

## Add below lines
binlog-do-db=SHUKLA               #Databases that you want to replicate
binlog-do-db=SHIRISH
binlog-ignore-db=mysql            # input the database that should be ignored for replication
binlog-ignore-db=test

## Cross varify below to exist we had already added
master-host = 192.168.8.10
master-user = replication
master-password = slave
master-port = 3306

# mysql -u root -px
mysql> stop slave;
mysql> grant replication slave on *.* TO ayam@'192.168.8.10' identified by 'x';
mysql> grant replication slave on *.* TO ayam@'192.168.8.20' identified by 'x';
mysql> GRANT ALL PRIVILEGES ON *.* TO replication@192.168.8.10;
mysql> GRANT ALL PRIVILEGES ON *.* TO replication@192.168.8.20;
mysql> GRANT ALL PRIVILEGES ON *.* TO replication;
mysql> CHANGE MASTER TO MASTER_HOST='192.168.8.10',MASTER_USER='replication',MASTER_PASSWORD='slave';
mysql> start slave;

ON SYSTEM-1
mysql> show slave status\G; < and cross varifie with as we done in PART-1

ON SYSTEM-2
mysql> show slave status\G; < and cross varifie with as we done in PART-1

CROSS Checking:

###################################### BASIC MYSQL COMMANDS ###############################
##Create database SHIRISH
mysql> create database SHIRISH;
##Create Tables into database SHIRISH
mysql> use SHIRISH;
mysql> create table LINUX_USERS(name char(20), age varchar(20));
##Display created table;
mysql> show tables;
##Insert data into table LINUX_USERS
mysql> insert into LINUX_USERS(name,age) values ('Shirish Shukla', 23)
##display created entry into table LINUX_USERS
mysql> select * from shukla;

# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
# AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ========================#
#                                          MYSQL -- BY Shirish Shukla #
#                                                   RHC Engineer 2010 #
#                                             shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
# "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#=====================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=====================================================================#

boot process Linux sort

2011-01-27T08:50:00.000-08:00

Boot Process in sort by Shirring Shukla

In sort boot process of linux OS ....

power on --> BIOS load into RAM --> BIOS moto is to load OS --> for that he perform POST inventry and calls CMOS to know boot order

---> after getting boot order BIOS load it whatever it finds in first sector of hdd into RAM this is what we called MBR

M ----------------------------- B ----------------------------------- R
<----------------------------- 512 bytes --------------------------->
+--------------BS------------+ +--------PT--------+ +----MN----+
                    446                  64                      2
M ------------------------------ B ----------------------------------- R

--> Exaine PT of MBR to know where is active partition (AP) -> Then BIOS load whatever it finds on BS of AP
--> BIOS then load 1SBL(1st satge boot loader) which were put there by anocanda during install time.
--> 1SBL gives CHS # of the /boot/boot.map to BIOS to load 2SBL(2st satge boot loader)
--> 2SBL examine the binary format of grub.conf and follows all instructions given there.
--> with the help of BIOS 2SBL loads Linux kernel vmlinuz-2.4.20-8 into the RAM
--> 2SBL uncompress kernal vmlinuz and filled it into ram waht we see in /proc dirr...
--> Now Linux Kernel is into RAM which is much powerfull than 2SBL and takes total control from it.
--> With the help of BIOS Kernal uncompresses the /boot/initrd-2.4.20-8.img to find filesystem driver.
-> Now HDd driver available and Kernel is into RAM
-> Now Kernel Load /sbin/init program into RAM.
-> /sbin/init* examines /etc/inittab and
                        1> run level (0-6 what ever is is defined) and run an script name
                        2> /etc/rc.d/rc.sysinit in a subshell of inittab shell
                        which calls /etc/sysconfig/network to load networking
                        and start various functions defined in /etc/init.d/functions
                        and Mounts all local filesystems from /etc/fstab and updates /etc/mtab
                        and now function of ec.sysinit ends
                        Short summary of what rc.sysinit does
                             ===================================== in sort waht done by rc.sysinit
                            hostname
                             system logs
                             date and time
                            keyboard
                             system font
                             swap partitions
                             usb
                             file system checks
                             mount the filesystems read/write
                        =====================================

                        3> /etc/rc.d/rc      { as a subshell }
                           /etc/rc.d/rc3.d/K*
                           /etc/rc.d/rc3.d/S* -->   start & stop of services
                           /etc/rc.d/rc.local -->

--> shell inittab is active and by defaults there are 6 mingettys out of which all entered into sleep state
--- except 1
---> this mingetty then executes the /bin/login process and is then it put into sleep state by init
---> and we get promped for username & password
--> * /bin/login execs /usr/bin/passwd which challenges for passwd from
    us which then does authentication and authorization using PAM
---> after Right username and password
---> mingetty then goes into zombie state and is killed by init
---> defined shell loads and we get our shell based command prompt:#$

# Faced any problem Feedback in above contact me
#============================Scratch=================================#
#                                                    AND Many More .....................Linux is Endless               #
#========================== Hope you Liked IT ==========================#
#                                                                                    BOOT PROCESS-- BY Shirish Shukla #
#                                                                                                                RHC Engineer 2010 #
#                                                                                                          shirish.linux@gmail.com #
#                                                                                                        shirishlinux.blogspot.com #
#                        "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#===================================================================#
#                       TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk   #
#===================================================================#

LOGWATCH LINUX

2011-01-27T08:17:00.000-08:00

logwatch - system log analyzer and reporter

--detail level 10/5/0              (high, med, low)
--debug level   0/1/..100
--service service-name/all          (more , seperated )
--print                             (Print output on screen)
--save /usr/mylogwatch_`date +%d-%b-%Y`
--mailto shirish@server.example.com
--range Yesterday/Today/all/Help
--archives                          (logwatch searches archived too like messages.1 etc..)
--logdir /var/op/logs/              (Locate your log dirs)

Config FILES (Source REDHAT)
       /usr/share/logwatch/
              This directory contains all the perl executables and configuration files shipped with
              the logwatch distribution.

       /etc/logwatch
              This directory contains local configuration files that override the default configura-
              tion. See MORE INFORMATION below for more information.
EXAMPLES
       logwatch --service ftpd-xferlog --range all --detail high --print --archives
              This will print out all FTP transfers that are stored in all current and archived xfer-
              logs.
       logwatch --service pam_pwdb --range yesterday --detail high --print
              This will print out login information for the previous day...

range
   --range today
   --range yesterday
   --range '4 hours ago for that hour'
   --range '-3 days'
   --range 'since 2 hours ago for those hours'
   --range 'between -10 and -2 days'
   --range 'Apr 15, 2005'
   --range 'first Monday in May'
   --range 'between 4/23/2005 and 4/30/2005'
   --range '2005/05/03 10:24:17 for that second'

# Faced any problem Feedback in above contact me
#============================Scratch===============================#
#                                                     AND Many More .....................Linux is Endless               #
#========================== Hope you Liked IT =========================#
#                                                                              CMND LOGRATATE-- BY Shirish Shukla #
#                                                                                                             RHC Engineer 2010 #
#                                                                                                           shirish.linux@gmail.com #
#                                                                                                         shirishlinux.blogspot.com #
#                         "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#==================================================================#
#                          TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk #
#==================================================================#

change date and time linux

2011-01-27T08:09:00.000-08:00

change date and time linux

============ Treating with date command =================

1> date 081811002007 [mmddhhmmyyyy]--To set the Linux clock to 11th-Aug-2007-11-AM
2> timeconfig --Set your TIMEZONE
3> hwclock --hc to sys--->-->To set the Linux[system]clock from the HW clock
4> hwclock --utc sys to hc -->To set the HWclock from the Linux[system] clock

touch -t yyyymmddhhmm filename

echo "DATE:" `date --date "today" +%d-%m-%Y`             <--DATE:20-12-2010
echo "DATE:" `date --date "yesterday" +%d-%m-%Y`
echo "DATE:" `date --date "+5 minutes ago" +%d-%m-%Y-%M` <--present -5 min
echo "DATE:" `date --date "-5minutes ago" +%d-%m-%Y-%M` <---Present +5 min
echo "DATE:" `date --date "1 month ago -5 minutes ago" +%d-%m-%Y-%M`
                                                         <--present -1 month +5 min

Some importnat journal use paramiters
%a --> Mon
%b --> Jan
%d --> date 01..31      %e --> 1..31
%H --> hour 0..23)      %k --> 1..23
%M --> minute (00..59)
%S --> Seconds(00..60)
%I --> hour 00..12)     %m --> 1-12
%Y --> year 2010        %y --> year 10(last 2 digit)
%p --> AM-PM            %p --> am-pm
%T --> %H:%M:%S

=================================== More n more ==================
%%--->a literal %
%a--->localeâs abbreviated weekday name (e.g., Sun)
%A--->localeâs full weekday name (e.g., Sunday)
%b--->localeâs abbreviated month name (e.g., Jan)
%B--->localeâs full month name (e.g., January)
%c--->localeâs date and time (e.g., Thu Mar 3 23:05:25 2005)
%C--->century; like %Y, except omit last two digits (e.g., 21)
%d--->day of month (e.g, 01)
%D--->date; same as %m/%d/%y
%e--->day of month, space padded; same as %_d
%F--->full date; same as %Y-%m-%d
%g--->last two digits of year of ISO week number (see %G)
%G--->year of ISO week number (see %V); normally useful only with %V
%h--->same as %b
%H--->hour (00..23)
%I--->hour (01..12)
%j--->day of year (001..366)
%k--->hour ( 0..23)
%l--->hour ( 1..12)
%m--->month (01..12)
%M--->minute (00..59)
%n--->a newline
%N--->nanoseconds (000000000..999999999)
%p--->localeâs equivalent of either AM or PM; blank if not known
%P--->like %p, but lower case
%r--->localeâs 12-hour clock time (e.g., 11:11:04 PM)
%R--->24-hour hour and minute; same as %H:%M
%s--->seconds since 1970-01-01 00:00:00 UTC
%S--->second (00..60)
%t--->a tab
%T--->time; same as %H:%M:%S
%u--->day of week (1..7); 1 is Monday
%U--->week number of year, with Sunday as first day of week (00..53)
%V--->ISO week number, with Monday as first day of week (01..53)
%w--->day of week (0..6); 0 is Sunday
%W--->week number of year, with Monday as first day of week (00..53)
%x--->localeâs date representation (e.g., 12/31/99)
%X--->localeâs time representation (e.g., 23:13:48)
%y--->last two digits of year (00..99)
%Y--->year
%z--->+hhmm numeric timezone (e.g., -0400)
%:z   -> +hh:mm numeric timezone (e.g., -04:00)
%::z -> +hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z -> numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z    -> alphabetic time zone abbreviation (e.g., EDT)

# Faced any problem Feedback in above contact me
#============================Scratch==============================#
#                                                     AND Many More .....................Linux is Endless               #
#========================== Hope you Liked IT =======================#
#                                                                                          CMDS DATE-- BY Shirish Shukla #
#                                                                                                                RHC Engineer 2010 #
#                                                                                                           shirish.linux@gmail.com #
#                                                                                                         shirishlinux.blogspot.com #
#                          "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#==================================================================#
#                          TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk #
#==================================================================#

LVM setup linux

2011-01-27T08:01:00.000-08:00

----LVM --------- --> Logical Volume Management -- Shirish Shukla

PV -- Physical Volume
VG -- Volume Group
LV -- Logical Volume

---------Create LVM partition------- /myvol/vo

# fdisk /dev/sda

create new partition 1200Mb of type LVM(8e)

# partprobe -s
# fdisk -l              (Check )

-------------LVM-----------

# pvcreate /dev/sda10
# vgcreate myvol   /dev/sda10   (will create VG "myvol")
# vgdisplay                      (Varify VG)
# lvcreate -L1000M -n vo myvol
# lvdisplay
    LV Name   /dev/myvol/vo

# mkfs.ext3 /dev/myvol/vo
# vi   /etc/fstab

Comment
Label=/home ....

and make below entry

/dev/myvol/vo    /home    ext3    defaults    1 2

#umount /home
#mount -a
#mount       (Varify   /home)

xxxxxxxxxxxxxxxxxxxx

Q: Resize LVM to 300M.

    Check lvm status by using
    # lvdisplay
    # vgdisplay
    # df –h

    Case I: current < 300M

    #lvextend   -L 300M /dev/myvol/vo
    #resize2fs /dev/myvol/vo
    #lvdisplay        …check lvsize
    #df   -h           ….varify size on /home

    Case II: current > 300M

    #umount /home
    #e2fsck   –f    /dev/myvol/vo
    #resize2fs   /dev/myvol/vo 300M
    #lvreduce   -L 300M   /dev/myvol/vo
            ---: type yes
    #lvdisplay      ..varify lv size must be 300M
    #mount -a
    #mount           …..varify
    #df -h             …..varify

# Faced any problem Feedback in above contact me
#======================== ===Scratch===============================#
#                                                     AND Many More .....................Linux is Endless               #
#========================== Hope you Liked IT =========================#
#                                         LVM-- BY Shirish Shukla #
#                                                                                                               RHC Engineer 2010 #
#                                              shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
#                           "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#==================================================================#
#                          TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk #
#==================================================================#

vsftpd configuration linux

2011-01-27T07:55:00.000-08:00

Replace your vsftpd.conf by below of myne ...

##!!!!!!!!!!!!!!!! vsftpd: - Shirish Shukla !!!!!!!!!!!!!!!!!!!!!##
#Clinet:
#GUI :gftp
#CLI :ftp

#Server Config:
#Default : /etc/vsftpd/vsftpd.conf
#Some Binary : /etc/vsftpd.conf

#Service:
#/etc/init.d/vaftpd start|stop|restart|condrestart|status
#/usr/sbin/vsftpd &

#vsftpd.conf
#Remember:
#1>Don't use space before or after '=' it's error
#2>All paramiter start from column 1 i.e no space before parameters..
#3>Any misspell result deman not starting
#4>YES/NO and yes/no dosent matter
#============================== vsftpd.conf ==========================
####An Ipportant minimum requirement .

listen=yes

###You FTP Banner
ftpd_banner=WellCome to Shirish Shukla Word OF FTP .
##Can Include File
#banner_file=/etc/vaftpd/ftpbanner
##You Can specify denied users mail id from file .
#deny_email_enable=YES
#banned_email_file=/etc/vsftpd/banned_emails

####=================== Main Configration ======================####
###By default only anon user is allowd #(ftp' and 'anonymous' are VLUs for anonymous.)
anonymous_enable=yes
##Input of anon password IF Default YES straight login no psw
#no_anon_password=YES
##FTP Default Home dir.. default below can change
#anon_root=/var/ftp/
##Dafault FTP username default below can change
#ftp_username=ftp

###Want VLU to use FTP
local_enable=yes
##Auth by PAM
pam_service_name=vsftpd

#       test: pam modulle have to be preseent
#       ldd `which vaftpd` |grep pam

###If local_enable=YES VLU can access to FTP after authentication
##Want VLU to access ther Home dir only..chroot them
#chroot_local_user=YES
##Want to unchroot some listed user
#chroot_list_enable=YES
#chroot_list_file=/etc/vsftpd/chroot_list
##Each users jail based on directory string in /etc/passwd.
#passwd_chroot_enable=NO
##Enabled, all non-anonymous[VLUs]rooted to /var/ftp
#guest_enable=NO
#guest_username=ftp
##Default root dir.. for anon same as anon_root
#local_root=/var/ftp

###Enable/Disable FTP Write command
write_enable=YES

###File dir upload permission by default 022
local_umask=755

###BY default below NO Anon user can upload and make dir..
#anon_upload_enable=YES
#anon_mkdir_write_enable=YES
###messages given to remote users when they enter into dir..
#dirmessage_enable=YES

###data transfer connection f#chown_uploads=YESrom 20
connect_from_port_20=YES
ftp_data_port=20

###If Need any upload to be owned by user shukla
#chown_uploads=YES
#chown_username=shukla

###Want a user totally isolated & unpreviledge user
#nopriv_user=ftpsecure

###Enable ascii uploadation and download Read in depth before
#enabiling this recomended...
#ascii_upload_enable=YES
#ascii_download_enable=YES

###Disable -R option of remote user so to avoid excessive IO
#ls_recurse_enable=NO

###listen vsftpd runs in standalone mode & listens on IPv4 sockets
##To Listen on both socket you ned to run 2 config file of vsftpd
##Make sure comented below
#listen_ipv6=YES

###User based Permission
##IF 'YES' Disable access of user listed in file userlist_file
#userlist_enable=NO
#userlist_file=/etc/vsftp.user_list
##Oppose above IF below 'NO' Enable All User listed in userlist_file only .
#userlist_deny=YES

#### IF Load another config dir same as vsftpd
#user_config_dir=/home/shukla/myfiles

####================== Logs =======================#
###Eable logging of any upload download
#xferlog_enable=NO

###Want log to be saved on my location
#xferlog_file=/var/log/vsftpd.log

###Logs in fromat standard ftpd xferlog
#xferlog_std_format=YES

#### =================== Fine Tuning Part ==================##
###Enable disable TCP-Wrapper based security
#tcp_wrappers=NO
#listen_address=default none
#       test: pam modulle have to be preseent
#       ldd `which vaftpd` |grep pam

###Limit use of FTP Access =0 [unlimited] you can limit by int value
#max_clients=0
#max_per_ip=0
###Timeout, in seconds, for a remote client to establish connection
#accept_timeout=30
#connect_timeout=60

###Limit session below are default you can change as per req .
#idle_session_timeout=600
#data_connection_timeout=120

###Maximum data transfer rate permitted, in bytes per second
#local_max_rate=0
#local_umask=077
#anon_max_rate=0
#anon_umask=077

##NO IF want disallow the PORT method of obtaining a data connection.
#port_enable=YES
##Set to YES if you want to disable the PORT security check that ensures that
##outgoing data connections can only connect to the client. Only enable if you
##know what you are doing!
#port_promiscuous=NO

# Faced any problem Feedback in above contact me
#======================== ===Scratch===============================#
#                                                     AND Many More .....................Linux is Endless                #
#========================== Hope you Liked IT ========================#
#                                            VSFTP -- BY Shirish Shukla #
#                                                                                                               RHC Engineer 2010 #
#                                              shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
#                             "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#==================================================================#
#                          TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk #
#==================================================================#

telnet in linux

2011-01-27T07:49:00.001-08:00

Telnet configuration in RHEL5
First check whether telnet-server rpm in installed,
# rpm -q telnet-server
telnet-server-0.17-38.el5
If it is installed, then edit
# vi /etc/xinet.d/telnet
change the line disable = yes to
disable = no
Then # service xinetd restart
Now We can able to telnet connection of linux system.
Note : It works for the system which is not protected with IPtables and Selinux
If you have iptables enabled. then please follow as below,
Make a rule to allow telnet from external clients
# iptables -I INPUT -p tcp --dport 23 -j ACCEPT
# service iptables save
# service iptables restart
Just give following command and make sure that rule is saved.
# iptables -L
This rule is to allow request coming to port number 23 i.e. telnet connections from any client.
============

Myne conclusion
1> off firewall
2> chkconfig krb5-telnet on
3> please not do not on krb5-telnet
4> service xinetd restart
5> do telnet my dude it will now work fine!

Have a niceva day!!!

:wq :)


# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
#                                                            AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ===========================#
#                                           TELNET -- BY Shirish Shukla #
#                                                    RHC Engineer 2010 #
#                                               shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
#    "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#===================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=====================================================================#

tar,zip,bzip,bzip2 linux commands

2011-01-27T07:48:00.000-08:00

================== Compress Archiever ===========================

==> tar
tar -cvf file.tar <source_files>       ----> tared
tar -tvf file.tar                ----> tabular view content of file
tar -xvf file.tar                ----> untar

==> compress & uncompress    >>> RH-9 absent in RHEL versions
tar -Zcvf file.tar.Z <source_file>    ----> compress
tar -Zxvf file.tar.Z               ----> uncompress

compress file.tar
uncompress file.tar.Z

==> zip & unzip
gip file.tar <source_name>        ----> ziped
gunzip file.tar.zip            ----> unziped

==> gzip & gunzip
tar -zcvf file.tar.gz <source_files> ----> gziped
tar -zxvf file.tar.gz

gzip file.tar
gunzip file.tar.gz


==> bzip2 & bunzip2
tar -jcvf file.tar.bz2 <source_name> ----> bziped
tar -jxvf file.tar.bz2            ----> bunziped

bzip2 file.tar.bzip2 <source_name>
bunzip2 file.tar.bzip2

===========>> Test file contents of compressed file
tar -tvf <filename>
    tar -Ztvf <filename>
    tar -ztvf <filename>
    tar -jtvf <filename>

zcat <filename>.gz
bcat <filename>.bz2   ---> absent in RHEL
cpio -idmv <filename>.cpio
zcat <filename>.cpio.gz | cpio -idmv

=================== Advanced =======================
1 line gungip and untar
# zcat backup.gz | tar -xvf -

# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
# AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ========================#
#                        CMNDS(tar,bzip, bzip2.. -- BY Shirish Shukla #
#                                                   RHC Engineer 2010 #
#                                             shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
# "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#=====================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=====================================================================#

nmap command magic linux

2011-01-27T07:43:00.001-08:00

nmap : Network exploration tool and security / port scanner
   Display open port number and protocol, service name, and state

   Syantax:
   nmap options hostnames/IPaddresses/networks
   -A, to enable OS and version detection(A detailed scan)
   -T4 for faster execuation of cmd
   -iL InputFileName contain list of IPS/hostname etc..
   --excludefile ExcludeFileName
   -sL: List Scan
   -sP: Ping Scan
   -pPortNo EG: -P22 etc...
   -e eth0 : scan particulat interface
   --packet-trace IP/Hostname : Show all packets sent and received
   --iflist : list all active links info MAc add etc..

If system ports have been changed for a particular application service
and is open then you can trace it
EG:
server1.example.com : vi /etc/ssh/sshd_conf
#Port 22 --> Port 1022 (For ssh changed to 22 to 1022 )

Now scan from system1.example.com:
# nmap -v -A server1.example.com (An detailed OS scan)

1022/tcp open ssh         OpenSSH 4.3 (protocol 2.0)

OR:
#nmap -T4 -sV server1.example.com (An detailed open port scan)

Examples:
# nmap -T4 -p22 192.168.8.10          :Scan for port 22
# nmap 192.168.8.10 |grep -i tcp      :Opend TCP ports

# nmap -sP 192.168.8.*                :Which hosts in my subnet
eg. output:
Host ntp.example.com (192.168.8.7) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host ns1.example.com (192.168.8.8) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host mail.example.com (192.168.8.9) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host server.example.com (192.168.8.10) appears to be up.
MAC Address: 00:0C:29:3C:4D:66 (VMware)
Host client.example.com (192.168.8.20) appears to be up.
Nmap finished: 256 IP addresses (5 hosts up) scanned in 9.375 seconds

# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
# AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ========================#
#                                       nmap cmd -- BY Shirish Shukla #
#                                                   RHC Engineer 2010 #
#                                             shirish.linux@gmail.com #
#                                           shirishlinux.blogspot.com #
# "Give Respect To Time One Day At Right Time, Time Will Respect You" #
#=====================================================================#
# TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=====================================================================#

fg and bg command linux

2011-01-27T07:39:00.000-08:00

=================== foreground background processes ====================
run process in backgrounbd foreground
commands :
1> (sleep 282828282 ) &                < - process 1
1> (sleep 9090909090 ) &              < - process 2

# jobs
# fg %1    ^Z       stop
# bg %1         start again in bg
# fg %1    start in fg
# kill %1     terminate %1 or
# fg %1     ^C    to terminitae command

# Faced any problem Feedback in above contact me
#===============================Scratch===============================#
#                                                            AND Many More .....................Linux is Endless                 #
#========================== Hope you Liked IT ===========================#
#                                            FG-BG -- BY Shirish Shukla #
#                                                       RHC Engineer 2010 #
#                                              shirish.linux@gmail.com #
#                                                                                                               shirishlinux.blogspot.com #
#                                     " Give Respect To Time One Day At Right Time, Time Will Respect You" #
#===================================================================#
#    TRy Hard theres nothing that are un-achievable by HARDdd-WORKkk     #
#=================================================================== #

remove spaces fom filename

2011-01-04T07:48:00.001-08:00

Having a space in the file name is never a good idea.
If you are in need to remove space from all file names
within your current directory you can use a following
command to do so:

ls | grep " " | while read -r f; do mv -i "$f" `echo $f | tr -d ' '`; done

In case that you wich to substitute space within a file
name to underscore ( or any other character ) use a following
command to do so:

ls | grep " " | while read -r f; do mv "$f" `echo $f | tr ' ' '_'`; done

How it works? ls and grep will feed while loop with all files within
a current working directory which contain a space in their file name.
In the body of the while loop we will next execute mv command a translate
it file destination with tr command. Make sure to keep -i option enabled
when using mv command to avoid accidentally overwrite files.

scripting sort hand

2011-01-04T07:46:00.001-08:00

>>>>>>>>>>>> count the occurences of a specific word in a .txt file in bash shell.

tr -s ' ' '\n' < myfile.txt | grep -c 'searchword'

cat mydr/myfiles-1-* |grep -c "searchtest"

>>>>>>>>>>>> Find Days in months(eg apr:30 days)

tmnth=$(cal 4 2010 | egrep -v '[A-Za-z]' | wc -w)

>>>>>>>>>>>> gunzip & untar in 1 cmd

cat May-2010.tar.gz | gunzip -d | tar -xvf -

<sorten>
gzcat test123.tar.gz | tar -xvf -

< REVERSE >
tar -zcvf   May-2010.tar.gz

IFS bash variable

2011-01-04T07:44:00.001-08:00

The IFS internal variable
One way around this problem is to change Bash's internal
IFS (Internal Field Separator) variable so that it splits
fields by something other than the default whitespace
(space, tab, newline), in this case, a comma.

eg:
#!/bin/bash
IFS=$',' # seperate input by comma
vals='/mnt,/var/lib/vmware/Virtual Machines,/dev,/proc,/sys,/tmp,/usr/portage,/var/tmp'
for i in $vals; do echo $i; done
unset IFS

with unset IFS, so that it returns to its default value.
This will avoid any potential problems that could arise
in the rest of your script.

$IFS (internal field separator) : This variable determines how Bash recognizes fields,
or word boundaries, when it interprets character strings.
$IFS defaults to whitespace (space, tab, and newline), but may be changed, for example,
to parse a comma-separated data file. Note that $* uses the first character held in $IFS.

Fields seperator:
echo $datapath | awk -F "/" '{print $NF}'|awk 'BEGIN { FS="[- . ]" } {print $1}'

The logic is that the intialisation
BEGIN{FS="[ ]|[;]|[,]"} ; OFS=","}
sets up the Field Separator variable FS as a regular expression which matches any one of " " ";" ","
and the Output Field Separator OFS to be ",".

Power of vi editor Linux

2010-11-28T01:59:00.000-08:00

Power of vi Editor
=========
# vim /home/shirish/myscripts/scratcher.sh <-- colorfull look
# vi /home/shirish/myscripts/scratcher.sh <-- simple
Moving through the text is usually possible with the arrow keys. If not, try:

h -> move Left
l -> move Right
k -> move up
j -> move down

shift+H : top of file (or :1 similarly you can go to any line by line number(n) :n)
shift+G : end of file (or :$)

dd       --> delete current line
5+dd   -> delete 5 line from current line (similarly n line)
5+dw   -> delete 5 words from current word
x         -> delete single character from current position
cc        -->cut all current line content & leave the editor in insert mode
C         --> delete all words from current position to end of line.
s         -->cur the current character and leave te curser in insert mode

yy       -->copy line
n+yy   --> copy n lines
pp       -->paste copied line etc..
n+pp   -->paste n times

Insert Mode:
1> i   or I (cpas i)
2> Insert button
3> a (+move curser to 1 position right)
4> A (+ move the curser at end of line)
5> o (+ a blank line below current)
6> O (+ a blank line above current)

Command mode: ESC button

:w   -> Save
ESC+z+z --> Save & exit
:wq -> Save & Exit
:q    -> Exit
:q!   -> Exit without Save
:w file2 will save the text to file2.
:wq! overrides read-only permission
/find -->Search string "find" use "n" to search new location
? find --> same as above but search in opposite dir
:1, $s/shirish/shukla/g -->replace shirish by shukla throught file

undo & redo:
esc+u --> undo
ctl+r   --> redo
esc . --> repeate the previous change

Bookmark

step 1> Go to the required word (type ESC+ma) you can use any lowercase a - z, A - Z, [ ect,..   note that a & A store diff bookmarks etc..
step 2>To go to bookmarked location (type ESC+ `+a ) note ` is above TAB button, similarly you can give various bookmarkes
* You can go to yu last edited line by --> ESC+`+ .

:marks   --> Will show your bookmarks in current file.

Quick Summary of Vim Bookmark Commands

    * ma –> Creates a bookmark called a
    * `a   –> Jump to the exact location (line and column) of the bookmark a
    * ‘a   –> Jump to the beginning of the line of the bookmark a
    * :marks –> Display all the bookmarks
    * :marks a –> Display the details of the bookmark with name a
      `. –> Jump to the exact location (line and column) where the last change was performed
    * ‘. –> Jump to the beginning of the line where the last change was performed

Advanced:

K --> Go to the man page of the word currently under the curser.

How to schedule cron job Linux

2010-11-28T01:44:00.000-08:00

Schedule Crontab jobs

Crontab
It's a unix solaris utility that tasks to be run automatically in background at regular interval.
Daemon: crond

Accessibality:
/usr/lib/cron/cron.allow -> Use can use if your name exist in this file
In absence of this file it's necessary that your name does not exist in
/usr/lib/cron/cron.deny.
And If only cron.deny exist but empty then all users can use crontab.
But if neither exists only root can use crontab.

Commnad:
crontab -l ->List crontab file
crontab -e ->Edit crontab file
crontab -r ->Remove crontab file

====Crontab file fields

* * * * * command to be executed

| | | | |
| | | | +----- day of week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)

Example:
0> Edit crontab for root
# Login as root
# crontab -e

1>Edit crontab for user shukla
# crontab -u shukla -e

2>Display crontab defined by user shukla
# crontab -u shukla -l

3>Delete shukla's tmp file /home/shukla/dumps/*.* every day at 3:30pm
# crontab -u shukla -e
30 15 * * * * rm /home/shukla/dumps/*

4>Do above every monday-wednesday at 3pm but only in mnth of august
# crontab -u shukla -e
* 15 * * 8 1-3 rm /home/shukla/dumps/*

5>Do above on 1,23 of aug
* 15 1,23 * 8 1-3 rm /home/shukla/dumps/*

6>Do Above at 10:10AM and 6:20pm everyday...
10,20 10,18 * * * rm /home/shukla/dumps/*

7> Sample tricky examples
>Run Every hour
0 * * * * ....
>Run every min
* * * * * * ....

>Run every 5 min
*/5 * * * * .....

>Run ever 2 hour interval eg:00:05, 02:05
5 */2 * * *

>Ever month except april
* * * jan-mar,5-12 * * OR
* * * 1-3,5-12 * *

>On every reboot display msg alert
@reboot wall "PC is going to REBOOT"

>Ever hour same above --->this will run 1st sec of every hr equivalent to (0 * * * *)
@hourly wall "PC is going to REBOOT"

Some similar too:
@yearly --> (0 0 1 1 *)
@annually --> (0 0 1 1 *)
@monthly --> (0 0 1 * *)
@weekly --> (0 0 * * 0)
@daily --> (0 0 * * *)
@midnight --> (0 0 * * *)

--Shirish Shukla

Linux History command tips & Tricks

2010-11-18T09:09:00.000-08:00

History Command Tips:

1>Generally # history displays only commands you tiped last Suppose you want time too then...?

# export HISTTIMEFORMAT='%F %T '
# history | more
1 2010-11-11 15:05:20 top
2 2010-11-11 15:05:25 man top
3 2010-11-11 15:05:29 free -m
4 2010-11-11 15:10:05 cat /proc/mdstat

2>Search last hosory by ctl+r and type command you typed in last
when comes just press enter or use arrow to edit and fire you command

#Press Ctrl+R from the command prompt,
(reverse-i-search)`man ': man Top
[Note: Press enter or edit as per your requirement]

3>#Repeat you previou command quick
way 1> use up arroy once
way 2> !! <- Enter
way 3> !-1 <- Enter
way 4> ctl+p <-Enter

4> quick sortcut
#!5 <- 5th commnds you used from history to check use #history |less
#!man <- latest commnad you used that started with man...
#export HISTCONTROL=ignoredups (ignore duplicates commnds from history)
#export HISTCONTROL=erasedups (remove duplicates commnds from history)
#export HISTCONTROL=ignorespace (ignore to add cmnds starting with space in history)
eg:
#export HISTCONTROL=ignorespace
# man dig
#history
1 pwd
2 man top
3 ...
but history does not store any command you start with space

5> Clear your history
# history -c

6> Disable to use of history
# export HISTSIZE=0
# history
no o/p

7> Enable history to not record specifics commnands
# export HISTIGNORE="man:ll:pwd:password:alias amgreat=clear:amgreat"
Now use above commands but history dosent save it.

8> control you history size ..
# vi /home/yourhome_dir/.bash_profile
HISTSIZE=450
HISTFILESIZE=450