Commands by idemal (1)

What's this? is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

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resize all JPG images in folder and create new images (w/o overwriting)
Convert all jpegs in the current directory into ~1024*768 pixels and ~ 150 KBytes jpegs

diff process output
Execute a process or list of commands in the given interval and output the difference in output.

Running scripts after a reboot for non-root users .
Sometimes we may want to run a script when a system reboots . We can simply do this by just scheduling the script using vixie cron with the @reboot option . e.g @reboot I use it to send me an alert message on our prod hosts to send an alert message when the system reboots . @reboot zaman uptime | echo `uptime` | mail -s "`uname -n` got rebooted"

rename files according to date created
The command renames all files in a certain directory. Renaming them to their date of creation using EXIF. If you're working with JPG that contains EXIF data (ie. from digital camera), then you can use following to get the creation date instead of stat. * Since not every file has exif data, we want to check that dst is valid before doing the rest of commands. * The output from exif has a space, which is a PITA for filenames. Use sed to replace with '-'. * Note that I use 'echo' before the mv to test out my scripts. When you're confident that it's doing the right thing, then you can remove the 'echo'... you don't want to end up like the guy that got all the files blown away. Credits:

doing some floating point math

To have only unique lines in a file

Get last sleep time on a Mac

Broadcast your shell thru ports 5000, 5001, 5002 ...
run 'nc yourip 5000', 'nc yourip 5001' or 'nc yourip 5002' elsewhere will produce an exact same mirror of your shell. This is handy when you want to show someone else some amazing stuff in your shell without giving them control over it.

Start another X session in a window
You might have Xnest (older) rather than Xephyr. You can experiment with other desktops eg: startx /usr/bin/start-kde -- /usr/bin/Xephyr :2 You can start X on a remote machine (although I'd recommend vnc for anything slower than a LAN): startx /usr/bin/ssh -X gnome-session -- /usr/bin/Xephyr :2 Or just start another X session locally talking to the remote backend:

Rotate all jpeg images in current folder, rename them to EXIF datetime and set files timestamp to EXIF datetime

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