sed extract every nth line. Generic is: sed -n 'STARTPOSITION,${p;n;*LINE}' foo where n;*LINE = how many lines. thus p;n;n; is "for every 3 lines" and p;n;n;n;n; is "for every 5 lines" Show Sample Output

This should work even if the output format changes.

List everyone who committed to a particular project, listed alphabetically. To list by commits, add -n to the shortlog. Show Sample Output

Recursively rename .JPG to .jpg using standard find and mv. It's generally better to use a standard tool if doing so is not much more difficult.

In bash, by pressing ALT+n and then a character x, x will be printed n times I know is not the same as the original command, but is correlated. Show Sample Output

If you don't have nl on your system, this achieves a similar effect, the default behavior in nl is to not number blank lines, but this does.

I needed to add a line to my crontab from within a script and didn't want to have to write my own temporary file. You may find you need to reload the crond after this to make the change take effect. e.g.: if [ -x /sbin/service ] then /sbin/service crond reload else CRON_PID=`ps -furoot | awk '/[^a-z]cron(d)?$/{print $2}'` if [ -n "$CRON_PID" ] then kill -HUP $CRON_PID fi fi The reason I had CRON_HOUR and CRON_MINS instead of numbers is that I wanted to generate a random time between midnight & 6AM to run the job, which I did with: CRON_HOUR=`/usr/bin/perl -e 'printf "%02d\n", int(rand(6))'` CRON_MINS=`/usr/bin/perl -e 'printf "%02d\n", int(rand(60));'`

Better -and faster- using bash printf. Show Sample Output

You can substitute /home/$USER with any path you like.

Replace 70 with the desired height. Replace 180 with the desired width. I put it in my bashrc, because by default my terminal is too small.

You're a developer - but it doesn't mean you have to slum it! Why not spice up your man page lookups by using a decent PDF viewer. I use 'xpdf' - maybe you prefer acroread, whatever, it's just as fast as plain dull ASCII on today's machines and you can still search for stuff - that's the main reason I use PDF and not PS.

Often you find some tty programs are messed up and confused about character encoding - 'man' is a common problem and sometimes displays weird characters for apostrophes, hyphens etc etc. Another class of programs that suffer from this are those that try to use the line drawing characters - eg RedHat's tty system admin functions such as system-config-firewall-tui system-config-network-tui etc. Adding 'LC_ALL=C' fixes most of these problems (as long as you want English! Perhaps speakers of other languages can add a comment here). For bonus points, I've added the '-c' option to the man command so that it ignores it's cache and re-computes the man page using the C locale.

connects to host via ssh and displays the live transfer speed, directing all transferred data to /dev/null needs pv installed Debian: 'apt-get install pv' Fedora: 'yum install pv' (may need the 'extras' repository enabled) Show Sample Output

You can use vim scp://root@example.com//file too in a simple case.

the sql command lpad and rpad using sed for lpad, invert the &_ with _&: ls / | sed -e :a -e 's/^.\{1,15\}$/_$/;ta' Show Sample Output

the sed way to print a linhe with 50 hyphens

Perl is installed by default on most modern OS when jot is not. Show Sample Output

sed already has an option for editing files in place and making backup copies of the old file. -i will edit a file in place and if you give it an argument, it will make a backup file using that string as an extension.

Change the number 50 to whatever number of characters you want. Change the character inside the double quotes to whatever you want printed.

Works in RHEL5 and derivatives.