Commands by mnikhil (27)

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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Remove a range of lines from a file

beep when a server goes offline
pings a server once per second, and beeps when the server is unreachable. Basically the opposite of: $ ping -a which would beep when a server IS reachable. You could also substitute beep with any command, which makes this a powerful alternative to ping -a: $ while true; do [ "$(ping -c1W1w1 2>/dev/null | awk '/received/ {print $4}')" = 1 ] && date || echo 'server is down!'; sleep 1; done which would output the date and time every sec until the ping failed, in which case it would echo. Notes: Requires beep package. May need to run as root (beep uses the system speaker) Tested on Ubuntu which doesn't have beep out of the box... $ sudo apt-get install beep

Batch resize all images in the current directory that are bigger than 800px, height or weight.
You need to install imagemagick. On Debian type: # apt-get install imagemagick

Remove all unused kernels with apt-get
Remove old kernels (*-generic and *-generic-pae) via apt-get on debian/ubuntu based systems. Tested on ubuntu 10.04 - 12.04.

Fork Bomb for Windows
Quick and dirty forkbomb for all flavors of windows Do not use in production. Replace start with a command of your choice, this will just open a new command prompt and is pretty tricky to stop once started

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Show the 1000*1000 and 1024*1024 size of HDs on system

Move all images in a directory into a directory hierarchy based on year, month and day based on exif information
This command would move the file "dir/image.jpg" with a "DateTimeOriginal" of "2005:10:12 16:05:56" to "2005/10/12/image.jpg". This is a literal example from the exiftool man page, very useful for classifying photo's. The possibilities are endless.

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Show permissions of current directory and all directories upwards to /
Useful if a different user cannot access some directory and you want to know which directory on the way misses the x bit.

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