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Learn the difference between single and double quotes

grep for minus (-) sign
Use flag "--" to stop switch parsing

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

continuously check size of files or directories

ssh autocomplete based on ~/.ssh/config
I use this in my bashrc to expand hosts defined in ~/.ssh/config: function _ssh_completion() { perl -ne 'print "$1 " if /^Host (.+)$/' ~/.ssh/config } complete -W "$(_ssh_completion)" ssh Here's a great article on how to setup your own ~/.ssh/config: http://blogs.perl.org/users/smylers/2011/08/ssh-productivity-tips.html

List top 100 djs from https://djmag.com/top100djs

Speed up builds and scripts, remove duplicate entries in $PATH. Users scripts are oftern bad: PATH=/apath:$PATH type of thing cause diplicate.

Delete all files by extension
This is a correction to https://www.commandlinefu.com/commands/view/22134 Use `-name` instead of `-iname`, because case-sensitivity is probably important when we're dealing with filenames. It's true that extensions are often capitalised (e.g., "something.JPG"), so choose whatever's appropriate. However, what is appropriate is the quoting of the name pattern, so the shell doesn't expand it incorrectly. Finally, `-delete` is clearer.

diff files while disregarding indentation and trailing white space
**NOTE** Tekhne's alternative is much more succinct and its output conforms to the files actual contents rather than with white space removed My command on the other hand uses bash process substitution (and "Minimal" Perl), instead of files, to first remove leading and trailing white space from lines, before diff'ing the streams. Very useful when differences in indentation, such as in programming source code files, may be irrelevant

Quick glance at who's been using your system recently
This command takes the output of the 'last' command, removes empty lines, gets just the first field ($USERNAME), sort the $USERNAMES in reverse order and then gives a summary count of unique matches.


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