Useful commands for everyday life in the Linux/Unix world

Commands and resources

Description

ftp://username:*passwd*@abc.yourwebsite_html

Ever wondered how to supply username and passwd as part of URL?

echo "754b9db19f79dbc4992f7166eb0f37ce filename"|md5sum -c

Check a file called filename against its md5 checksum. There is a double space between the sum and file name in the argument to echo– this argument is in fact the output produced by “md5sum filename”.

bzcat filename.tar.bz2 | tar xvf - ( same as tar xvjf filename.tar.bz2)

Decompress and extract a tarred bzipped file

ssh-keygen -p

change ssh-agent passphrase

kill -1 ‘cat /var/run/syslogd.pid‘

Refresh the syslog process

for i in `ls` ; do if [ -d "$i" ]; then echo "$i"; fi; done

List subdirectories in the current directory

for i in `ls -la *.java *.html *.pdf|grep 'Feb 19'|awk '{print $9}'`; do scp $i Othermachine:MyStuff/;done

Find the files in the current directory with modification stamp of 'Feb 19' and copy them, using scp, to Othermachine:MyStuff/

a2ps --columns=2 -j -o filename.ps filename.txt

Convert a text file to postscript, double column

crontab fields: MINUTE(0-59) HOUR(0-23) DAYOFMONTH(1-31) MONTHOFYEAR(1-12) DAYOFWEEK(0-6) Note 0 = Sunday

Crontab fields.

touch -t 0104140000 /tmp/stamp

set timestamp of /tmp/stamp to April 14,00:00, 2001

touch -t 04140000 /tmp/stamp

set timestamp of /tmp/stamp to April 14, 00:00

scp `find ./ -newer file.txt -depth -follow -type f` igraine:CS2/.

Find all files starting at ./ that have modification times after 'file.txt' and scp them to destination

grep probability `find ./ -name '*'.tex -print`

grep oil `find ./ -name '*.tex' -print`

cat ex0.tr|grep 'tcp\|ack'|grep ' 2 3 \| 3 2 '

<meta http-equiv="Refresh" content="10;url=http://www.yourpage.com/" >

Refresh page every 10 seconds

latex2html -long_titles 5 -no_subdir -no_navigation -prefix "myfile” myfile .tex

Convert LaTex to html using latex2html.

find ./ -name '*.log' -print |xargs rm -f

Delete all .log files, descending down from the current directory node

find ./ -type f -atime 100

Files not accessed in 100 days

find ./ -name '*.nb'|cpio -ovH tar >nb.tar

Tar archive *.nb files

find /etc -newer back.tar -depth -follow -type f 2>/dev/null

Find all files in /etc and subdirectories that have modification times later than that of back.tar

find ./ -ctime -1 -type f -exec ls -la {} \;

find . -name "*" -exec grep -l "some text" {} ";"

Find some text within an unknown file and display the name of that file.

find ./ -ctime -1 -type f -exec scp {} linux1: \;

Find files with modification times within the last 24 hours and scp them to some destination

smbclient -L 192.168.1.12

Check available shares on smb server 192.168.1.12

rpm -q --whatrequires libpq.so.3

List of rpm packages that requires libpq.so.3

rpm -q --whatprovides libpq.so.3

rpm package that provides libpq.so.3

rpm -qlp /usr/local/synce-kde-0.6.1-1.i386.rpm

List files in rpm package

rpm -qp --filesbypkg /usr/local/synce-kde-0.6.1-1.i386.rpm

List files in rpm package

rpm -qpR /usr/local/synce-kde-0.6.1-1.i386.rpm

List packages on which this package depends

rpm -qpi /usr/local/synce-kde-0.6.1-1.i386.rpm

Extract description of the package

/sbin/ldconfig -p

List all directories/libraries in current cache

cp /var/spool/mail/yourlogin newmail; cat newmail | formail -t -s procmail -f

TO MANUALLY PROCESS spooled mail through procmail, you need to pipe it through formail, not procmail directly. Formail splits the spool file into individual messages and pipes each of them through procmail.

mpg123 -w xyz.wav xyz.mp3

convert mp3 file to wav file

sox a.wav a.cdr

convert .wav file to .cdr format for cdrecord to handle it

cdrecord -v speed=32 dev=0,0,0 -audio a.cdr x.cdr y.cdr z.cdr

Record a bunch of .cdr files to CD

cdrdao write --driver generic-mmc --device 0,0,0 --speed 24 --eject videocd.cue

Burn a Video CD, assuming appropriate directory structure has been set up

ls -l | sort -nr -k 5,5 (same as ls -laS)

Sort files by size

for i in `ls *.exe`; do basename $i |sed -e 's/\(.*\)\..*/\1/g'; done

Strip filenames of .exe extension

cat f | tr -s '[:blank:]' '_'

Replace horizontal white space in f by _ (underscore)

ls -lA --time-style=+%Y%m%d-%T

Display times in file listings in the format 20040829-13:57:09

#!/usr/bin/perl

open(LIST, "ls -1 * |");

while (<LIST>) {
push(@files, $_);
}
while (@files) {
$f = splice(@files, rand @files, 1); print "$f";
}

List files in a directory in random order. The ”ls” command lists files in some sorted order, so if you want a randomized list, you can use this script.

#!/bin/sh

#get current date – used as backup file prefix
DATE=`date +%d%h%Y`

#work direcory
cd /home/Myname

#Read MANIFEST-DAILY file, get directories to be backed up, and
#tar all the files modified in the last one day.

for i in `cat /home/Myname/Misc/Backup/MANIFEST-DAILY`; do tar rf /home/Myname/$DATE.tar `find $i -ctime -1 -depth -type f`; done

#zip it
gzip /home/Myname/$DATE.tar

#assumes ssh-agent doesn't need passphrase from user
eval `ssh-agent`

scp /home/Myname/$DATE.tar.gz remotemachine:Backup/

#kill ssh-agent – you don't want too many hanging around
kill -9 $SSH_AGENT_PID

Shell script to scp non-interactively files to a remote machine. Assumes that there are NO passphrases for ssh-agent. The script finds files modified during the last day, from directories listed in the MANIFEST-DAILY plain text file, creates] a gzipped tar file and sends them to the remote machine. Useful for daily cron job.

cat page.css|tr '\015' '\n' >page.css.0

replace those annoying ^M characters in a file by \n

dd if=/dev/cdrom of=/somewhere/name_of.iso

Will copy a CD to an ISO image file

mount /somewhere/name_of.iso /mnt/iso/ -t iso9660 -o loop

Will mount an ISO image file at mount point /mnt/iso