E-Wikipedia

A-Z Index of the Apple OS X command line

2010-05-07T12:30:00.000-07:00

The tcsh command shell of Darwin (the open source core of OSX)

alias     Create an alias

alloc     List used and free memory

awk       Find and Replace text within file(s)

basename  Convert a full pathname to just a folder path

bash      Bourne-Again SHell (Linux)

bless     Set volume bootability and startup disk options.

break     Exit from a loop

cal       Display a calendar

case      Conditionally perform a command

cat       Display the contents of a file

cd        Change Directory

chflags   Change a file or folder's flags.

chgrp     Change group ownership

chmod     Change access permissions

chown     Change file owner and group

chroot    Run a command with a different root directory

cksum     Print CRC checksum and byte counts

clear     Clear terminal screen

cmp       Compare two files

comm      Compare two sorted files line by line

complete  Edit a command completion [word/pattern/list]

continue  Resume the next iteration of a loop

cp        Copy one or more files to another location

cron      Daemon to execute scheduled commands

crontab   Schedule a command to run at a later date/time

cut       Divide a file into several parts

date      Display or change the date & time

dc        Desk Calculator

dd        Data Dump - Convert and copy a file

df        Display free disk space

diff      Display the differences between two files

diff3     Show differences among three files

dig       DNS lookup

dirname   Convert a full pathname to just a path

dirs      Display list of remembered directories

diskutil  Disk utilities - Format, Verify, Repair

ditto     Copy files and folders

dscl      Directory Service command line utility

du        Estimate file space usage

echo      Display message on screen

ed        A line-oriented text editor (edlin)

enable    Stop or start printers and classes.

env       Set environment and run a utility

eval      Evaluate several commands/arguments

exec      Execute a command

exit      Exit the shell

expect    Programmed dialogue with interactive programs

          Also see AppleScript

expand    Convert tabs to spaces

expr      Evaluate expressions

false     Do nothing, unsuccessfully

fdisk     Partition table manipulator for Darwin UFS/HFS/DOS

find      Search for files that meet a desired criteria

fmt       Reformat paragraph text

fold      Wrap text to fit a specified width

for       Expand words, and execute commands

foreach   Loop, expand words, and execute commands

fsck      Filesystem consistency check and repair

fs_usage  Filesystem usage (process/pathname)

ftp       Internet file transfer program

GetFileInfo Get attributes of HFS+ files

getopt    Parse positional parameters

goto      Jump to label and continue execution

grep      Search file(s) for lines that match a given pattern

groups    Print group names a user is in

gzip      Compress or decompress files

head      Display the first lines of a file

hdiutil   Manipulate iso disk images

history   Command History

hostname  Print or set system name

id        Print user and group names/id's

if        Conditionally perform a command

info      Help info

install   Copy files and set attributes

jobs      List active jobs

join      Join lines on a common field

kill      Stop a process from running

l         List files in long format (ls -l)

ll        List files in long format, showing invisible files (ls -la)

less      Display output one screen at a time

ln        Make links between files (hard links, symbolic links)

locate    Find files

logname   Print current login name

login     log into the computer

logout    Exit a login shell (bye)

lpr       Print files

lprm      Remove jobs from the print queue

lpstat    Printer status information

ls        List information about file(s)

lsbom     List a bill of materials file

lsof      List open files

man       Help manual

mkdir     Create new folder(s)

mkfifo    Make FIFOs (named pipes)

more      Display output one screen at a time

mount     Mount a file system

mv        Move or rename files or directories

net       Manage network resources

nice      Set the priority of a command

nohup     Run a command immune to hangups

onintr    Control the action of a shell interrupt

open      Open a file/folder/URL/Application

osascript Execute AppleScript

passwd    Modify a user password

paste     Merge lines of files

pbcopy    Copy data to the clipboard

pbpaste   Paste data from the Clipboard

pico      Simple text editor

ping      Test a network connection

pmset     Power Management settings

popd      Restore the previous value of the current directory

pr        Convert text files for printing

printenv  Print environment variables

printf    Format and print data

ps        Process status

pushd     Save and then change the current directory

pwd       Print Working Directory

quota     Display disk usage and limits

rcp       Copy files between machines.

repeat    Execute a command multiple times

rm        Remove files

rmdir     Remove folder(s)

rpm       Remote Package Manager

rsync     Remote file copy - Sync file tree (also RsyncX)

say       Convert text to audible speech

sched     Schedule a command to run at a later time.

screencapture Capture screen image to file or disk

sdiff     Merge two files interactively

security  Administer Keychains, keys, certificates and the Security framework

sed       Stream Editor

set       Set a shell variable = value

setenv    Set an environment variable = value

setfile   Set attributes of HFS+ files

shift     Shift positional parameters

shutdown  Shutdown or restart OS X

sleep     Delay for a specified time

softwareupdate System software update tool

sort      Sort text files

split     Split a file into fixed-size pieces

stop      Stop a job or process

su        Substitute user identity

sudo      Execute a command as another user

sum       Print a checksum for a file

switch    Conditionally perform a command

tail      Output the last part of files

tar       Tape ARchiver

tee       Redirect output to multiple files

test      Condition evaluation

time      Measure Program Resource Use

touch     Change file timestamps

traceroute Trace Route to Host

tr        Translate, squeeze, and/or delete characters

true      Do nothing, successfully

tty       Print filename of terminal on stdin

type      Describe a command

umask     Users file creation mask

umount    a device

unalias   Remove an alias

uname     Print system information

unexpand  Convert spaces to tabs

uniq      Uniquify files

units     Convert units from one scale to another

unset     Remove variable or function names

unsetenv  Remove environment variable

users     Print login names of users currently logged in

uuencode  Encode a binary file

uudecode  Decode a file created by uuencode

vi        Text Editor

wc        Print byte, word, and line counts

where     Report all known instances of a command

which     Locate a program file in the user's path

while     Execute commands

who       Print all usernames currently logged on

whoami    Print the current user id and name (`id -un')

xargs     Execute utility - passing arguments

yes       Print a string until interrupted

A-Z Index of the Linux BASH command line

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alias    Create an alias

apropos  Search Help manual pages (man -k)

awk      Find and Replace text, database sort/validate/index



break    Exit from a loop

builtin  Run a shell builtin

bzip2    Compress or decompress named file(s)

cal      Display a calendar

case     Conditionally perform a command

cat      Display the contents of a file

cd       Change Directory

cfdisk   Partition table manipulator for Linux

chgrp    Change group ownership

chmod    Change access permissions

chown    Change file owner and group

chroot   Run a command with a different root directory

cksum    Print CRC checksum and byte counts

clear    Clear terminal screen

cmp      Compare two files

comm     Compare two sorted files line by line

command  Run a command - ignoring shell functions

continue Resume the next iteration of a loop

cp       Copy one or more files to another location

cron     Daemon to execute scheduled commands

crontab  Schedule a command to run at a later time

csplit   Split a file into context-determined pieces

cut      Divide a file into several parts

date     Display or change the date & time

dc       Desk Calculator

dd       Data Dump - Convert and copy a file

declare  Declare variables and give them attributes

df       Display free disk space

diff     Display the differences between two files

diff3    Show differences among three files

dig      DNS lookup

dir      Briefly list directory contents

dircolors Colour setup for `ls'

dirname  Convert a full pathname to just a path

dirs     Display list of remembered directories

du       Estimate file space usage

echo     Display message on screen

egrep    Search file(s) for lines that match an extended expression

eject    Eject removable media

enable   Enable and disable builtin shell commands

env      Environment variables

ethtool  Ethernet card settings

eval     Evaluate several commands/arguments

exec     Execute a command

exit     Exit the shell

expand   Convert tabs to spaces

export   Set an environment variable

expr     Evaluate expressions

false    Do nothing, unsuccessfully

fdformat Low-level format a floppy disk

fdisk    Partition table manipulator for Linux

fgrep    Search file(s) for lines that match a fixed string

file     Determine file type

find     Search for files that meet a desired criteria

fmt      Reformat paragraph text

fold     Wrap text to fit a specified width.

for      Expand words, and execute commands

format   Format disks or tapes

free     Display memory usage

fsck     File system consistency check and repair

ftp      File Transfer Protocol

function Define Function Macros

gawk     Find and Replace text within file(s)

getopts  Parse positional parameters

grep     Search file(s) for lines that match a given pattern

groups   Print group names a user is in

gzip     Compress or decompress named file(s)

hash     Remember the full pathname of a name argument

head     Output the first part of file(s)

history  Command History

hostname Print or set system name

id       Print user and group id's

if       Conditionally perform a command

ifconfig Configure a network interface

import   Capture an X server screen and save the image to file

install  Copy files and set attributes

join     Join lines on a common field

kill     Stop a process from running

less     Display output one screen at a time

let      Perform arithmetic on shell variables

ln       Make links between files

local    Create variables

locate   Find files

logname  Print current login name

logout   Exit a login shell

look     Display lines beginning with a given string

lpc      Line printer control program

lpr      Off line print

lprint   Print a file

lprintd  Abort a print job

lprintq  List the print queue

lprm     Remove jobs from the print queue

ls       List information about file(s)

lsof     List open files

make     Recompile a group of programs

man      Help manual

mkdir    Create new folder(s)

mkfifo   Make FIFOs (named pipes)

mkisofs  Create an hybrid ISO9660/JOLIET/HFS filesystem

mknod    Make block or character special files

more     Display output one screen at a time

mount    Mount a file system

mtools   Manipulate MS-DOS files

mv       Move or rename files or directories

netstat  Networking information

nice     Set the priority of a command or job

nl       Number lines and write files

nohup    Run a command immune to hangups

nslookup Query Internet name servers interactively

passwd   Modify a user password

paste    Merge lines of files

pathchk  Check file name portability

ping     Test a network connection

popd     Restore the previous value of the current directory

pr       Prepare files for printing

printcap Printer capability database

printenv Print environment variables

printf   Format and print data

ps       Process status

pushd    Save and then change the current directory

pwd      Print Working Directory

quota    Display disk usage and limits

quotacheck Scan a file system for disk usage

quotactl Set disk quotas

ram      ram disk device

rcp      Copy files between two machines.

read     read a line from standard input

readonly Mark variables/functions as readonly

remsync  Synchronize remote files via email

return   Exit a shell function

rm       Remove files

rmdir    Remove folder(s)

rsync    Remote file copy (Synchronize file trees)

screen   Terminal window manager

scp      Secure copy (remote file copy)

sdiff    Merge two files interactively

sed      Stream Editor

select   Accept keyboard input

seq      Print numeric sequences

set      Manipulate shell variables and functions

sftp     Secure File Transfer Program

shift    Shift positional parameters

shopt    Shell Options

shutdown Shutdown or restart linux

sleep    Delay for a specified time

sort     Sort text files

source   Run commands from a file `.'

split    Split a file into fixed-size pieces

ssh      Secure Shell client (remote login program)

strace   Trace system calls and signals

su       Substitute user identity

sum      Print a checksum for a file

symlink  Make a new name for a file

sync     Synchronize data on disk with memory

tail     Output the last part of files

tar      Tape ARchiver

tee      Redirect output to multiple files

test     Evaluate a conditional expression

time     Measure Program running time

times    User and system times

touch    Change file timestamps

top      List processes running on the system

traceroute Trace Route to Host

trap     Run a command when a signal is set(bourne)

tr       Translate, squeeze, and/or delete characters

true     Do nothing, successfully

tsort    Topological sort

tty      Print filename of terminal on stdin

type     Describe a command

ulimit   Limit user resources

umask    Users file creation mask

umount   Unmount a device

unalias  Remove an alias

uname    Print system information

unexpand Convert spaces to tabs

uniq     Uniquify files

units    Convert units from one scale to another

unset    Remove variable or function names

unshar   Unpack shell archive scripts

until    Execute commands (until error)

useradd  Create new user account

usermod  Modify user account

users    List users currently logged in

uuencode Encode a binary file

uudecode Decode a file created by uuencode

v        Verbosely list directory contents (`ls -l -b')

vdir     Verbosely list directory contents (`ls -l -b')

vi       Text Editor

watch    Execute/display a program periodically

wc       Print byte, word, and line counts

whereis  Report all known instances of a command

which    Locate a program file in the user's path.

while    Execute commands

who      Print all usernames currently logged in

whoami   Print the current user id and name (`id -un')

Wget     Retrieve web pages or files via HTTP, HTTPS or FTP

xargs    Execute utility, passing constructed argument list(s)

yes      Print a string until interrupted

Uninstalling RMP

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Uninstalling a package is just as simple as installing one. Type the following
command at a shell prompt:

rpm -e foo

Note

Notice that we used the package namefoo, not the name of the original package
filefoo-1.0-1.i386.rpm. To uninstall a package, replace foo with the actual
package name of the original package.

You can encounter a dependency error when uninstalling a package if another
installed package depends on the one you are trying to remove. For example:

error: Failed dependencies: foo is needed by (installed)
bar-2.0.20-3.i386.rpm

To make RPM ignore this error and uninstall the package anyway (which may
break the package dependent on it) use the --nodeps option.

Unresolved Dependency

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RPM packages may sometimes depend on other packages, which mean that they
require other packages to be installed to run properly. If you try to install a
package which has an unresolved dependency, output similar to the following is
displayed:

error: Failed dependencies: bar.so.2 is needed by foo-
1.0-1 Suggested
resolutions: bar-2.0.20-3.i386.rpm

If you are installing a package from the Red Hat Enterprise Linux CD-
ROM set, it usually suggests the package(s) needed to resolve the dependency.
Find the suggested package(s) on the Red Hat Enterprise Linux CD-
ROMs or from Red Hat Network, and add it to the command:

rpm -ivh foo-1.0-1.i386.rpm bar-2.0.20-3.i386.rpm

If installation of both packages is successful, output similar to the following is
displayed:

Preparing...
########################################### [100%]
1:foo
########################################### [ 50%]
2:bar

########################################### [100%]

If it does not suggest a package to resolve the dependency, you can try the –
redhat provides option to determine which package contains the required
file. You need the rpmdb-redhat package installed to use this option.

rpm -q --redhatprovides bar.so.2

If the package that contains bar.so.2 is in the installed database from the
rpmdb-redhat package, the name of the package is displayed

bar-2.0.20-3.i386.rpm

To force the installation anyway (which is not recommended since the package
may not run correctly), use the --nodeps option.

Conflicting Files

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If you attempt to install a package that contains a file which has already been
installed by another package, the following is displayed:

Preparing...
########################################### [100%]
file
/usr/bin/foo from install of foo-1.0-1 conflicts
with file from package bar-2.0.20

To make RPM ignore this error, use the --replacefiles option:

rpm -ivh --replacefiles foo-1.0-1.i386.rpm

Package Already Installed

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If a package of the same name and version is already installed, the following
output is displayed:

Preparing...
########################################### [100%]
package
foo-1.0-1 is already installed

However, if you want to install the package anyway, you can use the --
replacepkgs option, which tells RPM to ignore the error: rpm -ivh --replacepkgs foo-1.0-1.i386.rpm

This option is helpful if files installed from the RPM were deleted or if you want
the original configuration files from the RPM to be installed.

Installing RPM

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RPM packages typically have file names like foo-1.0-1.i386.rpm. The file name
includes the package name (foo), version (1.0), release (1), and architecture
(i386). To install a package, log in as root and type the following command at a shell prompt:

rpm -ivh foo-1.0-1.i386.rpm

Alternatively, the following command can also be used:

rpm -Uvh foo-1.0-1.i386.rpm

If the installation is successful, the following output is displayed:

Preparing...
########################################### [100%]
1:foo ###########################################
[100%]

As you can see, RPM prints out the name of the package and then prints a
succession of hash marks as a progress meter while the package is installed. The
signature of a package is checked automatically when installing or upgrading a
package. The signature confirms that the package was signed by an authorized

party. For example, if the verification of the signature fails, an error message
such as the following is displayed:

error: V3 DSA signature: BAD, key ID 0352860f

If it is a new, header-only, signature, an error message such as the following is displayed:

error: Header V3 DSA signature: BAD, key ID 0352860f

If you do not have the appropriate key installed to verify the signature, the
message contains the word NOKEY such as:

warning: V3 DSA signature: NOKEY, key ID 0352860f

Warning
If you are installing a kernel package, you should use rpm -ivh instead.

Finding RPM Packages

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Before using any RPM packages, you must know where to find them. An
Internet search returns many RPM repositories, but if you are looking for RPM
packages built by Red Hat, they can be found at the following locations:

The Red Hat Enterprise Linux CD-ROMs
The Red Hat Errata Page available at
http://www.redhat.com/apps/support/errata/ Red Hat Network

Using RPM

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RPM has five basic modes of operation (not counting package building):
installing, uninstalling, upgrading, querying, and verifying. This section contains
an overview of each mode.

RPM Design Goals

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The RPM Package Manager (RPM) is an open packaging system, which runs on
Red Hat Enterprise Linux as well as other Linux and UNIX systems.
Red Hat, Inc. encourages other vendors to use RPM for their own products.
RPM is distributed under the terms of the GPL. The utility works only with
packages built for processing by the rpm package. For the end user, RPM makes
system updates easy. Installing, uninstalling, and upgrading RPM packages can
be accomplished with short commands. RPM maintains a database of installed
packages and their files, so you can invoke powerful queries and verifications on
your system. If you prefer a graphical interface, you can use the Package
Management Tool to perform many RPM
commands.

Important

When installing a package, please ensure it is compatible with your operating system
and architecture. This can usually be determined by checking the package name.

During upgrades, RPM handles configuration files carefully, so that you never
lose your customizations — something that you cannot accomplish with regular
.tar, .gz files. For the developer, RPM allows you to take software source
code and package it into source and binary packages for end users. This process
is quite simple and is driven from a single file and optional patches that you
create. This clear delineation between pristine sources and your patches
along with build instructions eases the maintenance of the package as new
versions of the software are released.

Note

Because RPM makes changes to your system, you must be logged in as root to install,
remove, or upgrade an RPM package.

To understand how to use RPM, it can be helpful to understand the design goals
of RPM:

Upgradability
With RPM, you can upgrade individual components of your system without

Completely reinstalling. When you get a new release of an operating system Based on RPM (such as Red Hat Enterprise Linux), you
do not need to reinstall on your machine (as you do with operating systems
based on other packaging systems). RPM allows intelligent, fully-
automated, in-place upgrades of your system. Configuration files in
packages are preserved across upgrades, so you do not lose your
customizations. There is no special upgrade files needed to upgrade a
package because the same RPM file is used to install and upgrade the
package on your system.

Powerful Querying
RPM is designed to provide powerful querying options. You can do
searches through your entire database for packages or just for certain files.
You can also easily find out what package a file belongs to and from
where the package came. The files an RPM package contains are in a
compressed archive, with a custom binary header containing useful
information about the package and its contents, allowing you to query
individual packages quickly and easily.

System Verification
Another powerful RPM feature is the ability to verify packages. If you are
worried that you deleted an important file for some package, you can
verify the package. You are then notified of any anomalies, if any — at
which point, you can reinstall the package if necessary. Any configuration
files that you modified are preserved during reinstallation.

Pristine Sources
A crucial design goal was to allow the use of pristine software
sources, as distributed by the original authors of the software. With RPM,
you have the pristine sources along with any patches that were used, plus
complete build instructions. This is an important advantage for several
reasons. For instance, if a new version of a program is released, you do not
necessarily have to start from scratch to get it to compile. You can look at
the patch to see what you might need to do. All the compiled-in defaults,
and all of the changes that were made to get the software to build properly,
are easily visible using this technique. The goal of keeping sources pristine
may seem important only for developers, but it results in higher qualitysoftware for end users, too.

Useful Websites For Linux

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Refer to the follow resources for more information.

http://acl.bestbits.at/ — Website for ACLs

Compatibility with Older Systems

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If an ACL has been set on any file on a given file system that files system has the
ext_attr attribute. This attribute can be seen using the following command:

tune2fs -l

A file system that has acquired the ext_attr attribute can be mounted with older
kernels, but those kernels do not enforce any ACLs which have been set.
Versions of the e2fsck utility included in version 1.22 and higher of the e2fsprogs
package (including the versions in Red Hat Enterprise Linux 2.1 and 4) can
check a file system with the ext_attr attribute. Older versions refuse to check it.

Archiving File Systems With ACLs

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Warning

The tar and dump commands do not backup ACLs.

The star utility is similar to the tar utility in that it can be used to generate
archives of files. The star package is required to use this utility. The command
line options for Star are as follows

Retrieving ACLs

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To determine the existing ACLs for a file or directory, use the getfacl command.
In the example below, the getfacl is used to determine the existing ACLs for a
file.

getfacl home/john/picture.png

The above command returns the following output:
# file: home/john/picture.png # owner: john # group: john user::rw- group::r-- other::r--

If a directory with a default ACL is specified, the default ACL is also displayed
as illustrated below.
john@main /]$ getfacl home/sales/# file: home/sales/ # owner: john # group:

john user::rw- user:barryg:r-- group::r-- mask::r-- other::r-- default:user::rwx
default:user:john:rwx default:group::r-x default:mask::rwx default:other::r-x

Setting Default ACLs

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To set a default ACL, add d: before the rule and specify a directory instead of a
file name. For example, to set the default ACL for the /share/ directory to read
and execute for users not
in the user group (an access ACL for an individual file can override it):

setfacl -m d:o:rx /share

Setting Access ACLs

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There are two types of ACLs: access ACLs and default ACLs. An access ACL
is the access control list for a specific file or directory. A default ACL can only
be associated with a directory; if a file within the directory does not have an
access ACL, it uses the rules of the default ACL for the directory. Default ACLs
are optional. ACLs can be configured:

Per user
Per group
Via the effective rights mask
For users not in the user group for the file

The setfacl utility sets ACLs for files and directories. Use the -m option to add or
modify the ACL of a file or directory:

setfacl -m

Rules () must be specified in the following formats. Multiple rules can
be specified in the same command if they are separated by commas.
u::
Sets the access ACL for a user. The user name or UID may be specified. The
user may be any valid user on the system.

g::
Sets the access ACL for a group. The group name or GID may be specified.
The group may be any valid group on the system.

m:
Sets the effective rights mask. The mask is the union of all permissions of the
owning group and all of the user and group entries.

o:
Sets the access ACL for users other than the ones in the group for the file.

White space is ignored. Permissions () must be a combination of the
characters r, w, and x for read, write, and execute. If a file or directory already
has an ACL, and the setfacl command is used, the additional rules are added to
the existing ACL or the existing rule is modified.
For example, to give read and write permissions to user andrius:

setfacl -m u:andrius:rw /project/somefile

To remove all the permissions for a user, group, or others, use the -x option and
do not specify any permission (s):

NFS

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By default, if the file system being exported by an NFS server supports ACLs and
the NFS client can read ACLs, ACLs are utilized by the client system. To disable
ACLs on NFS shares when configuring the server, include the no_acl option in
the /etc/exports file. To disable ACLs on an NFS share when mounting it on a
client, mount it with the no_acl option via the command line or the /etc/fstab file.

Mounting File Systems

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Before using ACLs for a file or directory, the partition for the file or directory
must be mounted with ACL support. If it is a local ext3 file system, it can be
mounted with the following command:
mount -t ext3 -o acl

For example:
mount -t ext3 -o acl /dev/VolGroup00/LogVol02 /work

Alternatively, if the partition is listed in the /etc/fstab file, the entry for the
partition can include the acl option:
LABEL=/work /work ext3 acl 1 2

If an ext3 file system is accessed via Samba and ACLs have been enabled for it,
the ACLs are recognized because Samba has been compiled with the --with-acl-
support option. No special flags are required when accessing or mounting a

Samba share.

Resizing a Partition

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Warning

Do not attempt to resize a partition on a device that is in use.

Before resizing a partition, boot into rescue mode (or unmount any partitions on
the device and turn off any swap space on the device). Start parted, where
/dev/sda is the device on which to resize the partition:

parted /dev/sda

View the current partition table to determine the minor number of the partition to
resize as well as the start and end points for the partition:

To resize the partition, use the resize command followed by the minor number
for the partition, the starting place in megabytes, and the end place in megabytes.
For example:

resize 3 1024 2048

Warning

A partition cannot be made larger than the space available on the device

After resizing the partition, use the print command to confirm that the partition
has been resized correctly, is the correct partition type, and is the correct file
system type. After rebooting the system into normal mode, use the command df
to make sure the partition was mounted and is recognized with the new size.

Removing a Partition

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Warning

Do not attempt to remove a partition on a device that is in use.

Before removing a partition, boot into rescue mode (or unmount any partitions
on the device and turn off any swap space on the device). Start parted, where
/dev/sda is the device on which to remove the partition:

parted /dev/sda

View the current partition table to determine the minor number of the partition to
remove:

Remove the partition with the command rm. For example, to remove the
partition with minor number 3:

rm 3

The changes start taking place as soon as you press Enter, so review the
command before committing to it. After removing the partition, use the print
command to confirm that it is removed from the partition table. You should also
view the output of

cat /proc/partitions

to make sure the kernel knows the partition is removed. The last step is to
remove it from the /etc/fstab file. Find the line that declares the removed
partition, and remove it from the file.

Standard Partitions using parted

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The utility parted allows users to:

View the existing partition table
Change the size of existing partitions
Add partitions from free space or additional hard drives

By default, the parted package is included when installing Red Hat Enterprise
Linux. To start parted, log in as root and type the command parted /dev/sda at a
shell prompt (where /dev/sda is the device name for the drive you want to
configure).

A device containing a partition must not be in use if said partition is to be
removed or resized. Similarly, when creating a new partition on a device, said
device must not be in use. For a device to not be in use, none of the partitions on
the device can be mounted, and any swap space on the device must not be
enabled. As well, the partition table should not be modified while it is in use
because the kernel may not properly recognize the changes. If the partition table
does not match the actual state of the mounted partitions, information could be
written to the wrong partition, resulting in lost and overwritten data. The easiest
way to achieve this is to boot your system in rescue mode. When prompted to
mount the file system, select Skip. Alternately, if the drive does not contain any
partitions in use (system processes that use or lock the file system from being
turn off all
unmounted), you can unmount them with the umount command and
the swap space on the hard drive with the swapoff command.

Table below contains a list of commonly used parted commands. The sections
that follow explain some of these commands and arguments in more detail.

Moving Swap Space

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To move swap space from one location to another, follow the steps for removing
swap space, and then follow the steps for adding swap space.

Removing a Swap File

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To remove a swap file:
1. At a shell prompt as root, execute the following command to disable the swap
file (where /swapfile is the swap file):

# swapoff -v /swapfile

2. Remove its entry from the /etc/fstab file.

3. Remove the actual file:

# rm /swapfile

Removing an LVM2 Logical Volume for Swap

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The swap logical volume cannot be in use (no system locks or processes on the
volume). The easiest way to achieve this is to boot your system in rescue mode.
Refer to for instructions on booting into rescue mode. When prompted to mount
the file system, select Skip.
To remove a swap volume group
(Assuming /dev/VolGroup00/LogVol02) is the swap volume you want to remove:

1. Disable swapping for the associated logical volume:

# swapoff -v /dev/VolGroup00/LogVol02

2. Remove the LVM2 logical volume of size 512 MB:

# lvm lvremove /dev/VolGroup00/LogVol02

3. Remove the following entry from the /etc/fstab file:

/dev/VolGroup00/LogVol02 swap swap defaults 0 0

4. Test that the logical volume has been extended properly:

# cat /proc/swaps # free

Reducing Swap on an LVM2 Logical Volume

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To reduce an LVM2 swap logical volume (assuming dev/VolGroup00/LogVol01
is the volume you want to extend):

1. Disable swapping for the associated logical volume:

# swapoff -v /dev/VolGroup00/LogVol01

2. Reduce the LVM2 logical volume by 512 MB:

# lvm lvreduce /dev/VolGroup00/LogVol01 -L -512M

3. Format the new swap space:

# mkswap /dev/VolGroup00/LogVol01

4. Enable the extended logical volume:

# swapon –va

5. Test that the logical volume has been reduced properly:

# cat /proc/swaps # free