Commands by SuperFly (20)

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Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Copy input sent to a command to stderr
In the above example 'muspi merol' (the output of the first rev command) is sent to stderr and 'lorem ipsum' (the output of the second rev command) is sent to stdout. rev reverse lines of a file or files. This use of tee allows testing if a program correctly handles its input without using files that hold the data.

List only executables installed by a debian package
I wanted to view only executables installed by a package. This seemed to work. There's got to be easier way, please share. Note: (1) Replace iptables with the package name of your interest (2) The command will trash any existing environment variable named 'lst' (3) Instead if you are interested in viewing just .ko or .so files installed by this package, then that would be easy: $ dpkg -L iptables | grep "\.[sk]o$" - CLI alternative to
NAME sprunge: command line pastebin: SYNOPSIS | curl -F 'sprunge=

Clear filesystem memory cache
Found here:

pngcrush all .png files in the directory
Find all pngs in directory structure and pngcrush them, none destructive. You can just remove the "{}.crush" part if you want destructive.

list all file extensions in a directory
... plus do a sort according frequency

Print today's date in ISO format without calling an external command (bash 4)

Short URLs with
No curl and no sed, just wget :)

Count items in JSON array
Pipe any JSON to jq, then count with the appropiate expression and use the | length on the array

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