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Generate a graph of package dependencies
Requires: imagemagick and graphviz On Debian systems, displays a graph of package dependencies. Works also with other image formats, like svg : $ apt-cache dotty bash | dot -T svg | display

Emptying a text file in one shot
% = buffer d = delete

Print one . instead of each line
this version only uses shell builtins

List just the executable files (or directories) in current directory
With zsh.

pipe output to notify-send
Route output to notify-send to show nice messages on the desktop, e.g. title and interpreter of the current radio stream

Mount important virtual system directories under chroot'ed directory
The command is useful when, e.g., booting an existing system with a rescue or installation CD where you need to chroot into the hard-disk and be able to do stuff which accesses kernel info (e.g. when installing Ubuntu desktop with LVM2 you need to mount and chroot the hard disk from a shell window in order to install packages and run initramfs inside chroot). The command assumes that /mnt/xxx is where the chroot'ed environment's root file system on the hard disk is mounted.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

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

Remove the first character of each line in a file

Perl One Liner to Generate a Random IP Address


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