shell-fu

Tip #894: Watch for Ubuntu 9.10 Launch

Thu, 29 Oct 2009 04:25:42 -0700

This script will run check a for the Ubuntu 9.10 launch once every 5 mins and let you know when it's available:

while [ 1 ]; do if [ -z "`curl -I "http://cdimage.ubuntu.com/releases/9.10/release/"|grep "404"`" ];
then kdialog --msgbox "9.10 Released"; exit; fi; sleep 300;  done

Tip #892: Check memory and swap from command line

Mon, 26 Oct 2009 03:21:56 -0700

Want to check the amount of used, free and total memory and swap from the command line? This script displays memory and swap information. Fully posix compliant and should work with all 2.[2-6].* kernels .

#fetch and process memory information
[ -f /proc/meminfo ] && {
Buffers=`grep -we 'Buffers' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
Cached=`grep -we 'Cached' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
MemFree=`grep -ie 'MemFree' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
MemTotal=`grep -ie 'MemTotal' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
SwapCached=`grep -ie 'SwapCached' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
SwapFree=`grep -ie 'SwapFree' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
SwapTotal=`grep -ie 'SwapTotal' /proc/meminfo | cut -d' ' -f2- | tr -d "[A-Z][a-z] "`
}
MEMUSED="$(( ( ( ( $MemTotal - $MemFree ) - $Cached ) - $Buffers ) / 1024 ))"
MEMTOTAL="$(( $MemTotal / 1024))"
MEMFREE="$(( $MEMTOTAL - $MEMUSED ))"
MEMPER="$(( ( $MEMUSED * 100 ) / $MEMTOTAL ))"
[ "$SwapTotal" -gt "1" ] && {
  SWAPUSED="$(( ( ( $SwapTotal - $SwapFree ) - $SwapCached ) / 1024 ))"
  SWAPTOTAL="$(( $SwapTotal / 1024))"
  SWAPFREE="$(( $SWAPTOTAL - $SWAPUSED ))"
  SWAPPER="$(( ( $SWAPUSED * 100 ) / $SWAPTOTAL ))" 
} || {
  SWAPUSED="0"
  SWAPTOTAL="0"
  SWAPPER="0" 
}

# display the information
/bin/echo
/bin/echo "Memory"
/bin/echo "Used: $MEMUSED"
/bin/echo "Free: $MEMFREE"
/bin/echo "Total: $MEMTOTAL"
/bin/echo
/bin/echo "Swap"
/bin/echo "Used: $SWAPUSED"
/bin/echo "Free: $SWAPFREE"
/bin/echo "Total: $SWAPTOTAL"
/bin/echo

Tip #889: Convert virtually any video into a DVD-valid MPEG2 stream

Mon, 26 Oct 2009 03:12:14 -0700

mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=dvd -vf scale=720:480,harddup -srate 48000 
-af lavcresample=48000 -lavcopts  
codec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=5000:keyint=18:aspect=16/9:acodec=ac3:abitrate=192 
-ofps 30000/1001 -o output.mpg input.extension

Options you might want to change:

scale: 720:480 for NTSC, 720:576 for PAL
ofps: 30000/1001 for NTSC, 25 for PAL
aspect: 16/9 or 4/3 depending on your video

Tip #885: Random password generator.

Wed, 16 Sep 2009 08:43:32 -0700

Generate a random 8 character password containing a-z, A-Z and 0-9:

egrep -ioam1 '[a-z0-9]{8}' /dev/urandom

Tip #882: Find last modified files on a filesystem

Tue, 15 Sep 2009 04:29:44 -0700

To find the last modified files in a directory you can use ls -ltr. To find the last modified file on a file system it will not work, but the following command will work:

find /etc -type f -printf "%T@ %T+ %p" | sort -n

Tip #879: Learn not to mistype ls

Mon, 14 Sep 2009 08:51:49 -0700

apt-get install sl

(or equivalent on your particular distro).

A "good" way of learning not to mistype ls.

Tip #878: Random xkcd comic

Mon, 14 Sep 2009 08:42:35 -0700

Displays a random xkcd comic. Requires ImageMagick.

wget http://dynamic.xkcd.com/comic/random/ -O -| grep <img src="http://imgs.xkcd.com/comics | 
 sed s/<img src="// | sed s/"[a-z]*.*// | wget -i - -O -| display

Tip #874: Count how many packages have been installed by pacman

Thu, 10 Sep 2009 13:48:31 -0700

Count how many packages have been installed by pacman:

pacman -Q|wc -l

Tip #873: Import ssh host keys without verification

Wed, 09 Sep 2009 12:58:15 -0700

Automatically import host keys for cluster of machines named 'all'

Using the 'dsh' command from the clusterit tools - http://sourceforge.net/projects/clusterit

RCMD_CMD_ARGS='-o VerifyHostKeyDNS=yes -o StrictHostKeyChecking=no' dsh -g all -e true

Tip #872: Reverse geocode with bash

Wed, 19 Aug 2009 10:12:26 -0700

The following bash script, which depends on lynx web browser, uses Google's reverse geocode service to find a nearby address given a latitude and longitude pair:

#!/bin/bash
# findnearest
# Usage: findnearest latitude longitude
# Ex.  findnearest  17.976227 -66.111016

lat=$1
long=$2
result=$(lynx -dump "http://maps.google.com/maps/geo?output=csv&oe=utf-8&ll=$lat,$long")
echo $result | cut -f3- -d,