Commands by mtrgrrl (1)

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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"

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

Get current stable kernel version string from kernel.org
depends on "jq" This is more reliable in my opinion.

Transforms a file to all uppercase.
Transforms a file to all uppercase.

Insert a line at the top of a text file without sed or awk or bash loops
Yet another way to add a line at the top a of text file with the help of the tac command (reverse cat).

write the output of a command to /var/log/user.log... each line will contain $USER, making this easy to grep for.
This command is useful if you want to copy the output of a series of commands to a file, for example if you want to pastebin the output from 'uname -a', 'lspci -vvv' and 'lsmod' for video driver trouble-shooting on your favorite Linux forum. 'log' takes all the following arguments as a command to execute, with STDOUT sent to /var/log/user.log. The command is echoed to the log before it is executed. The advantages of using logger (as opposed to appending output from commands to a file) are 1) commands are always appended to the logs... you don't have to worry about clobbering your log file accidentally by using '>' rather than '>>' 2) logs are automatically cleaned up by logrotate. The following functions allow you to mark the start and end of a section of /var/log/user.log. $ startlog() { export LOGMARK=$(date +%Y.%m.%d_%H:%M:%S); echo "$LOGMARK.START" | logger -t $USER; } then $ endlog() { echo "$LOGMARK.END" | logger -t $USER; } printlog will print all lines between $LOGMARK.START and $LOGMARK.END, removing everything that is prepended to each line by logger. $ printlog() { sudo sed -n -e "/$LOGMARK.START/,/$LOGMARK.END/p" /var/log/user.log| sed "s/.*$USER: //"; } The following command should dump just about all the information that you could possibly want about your linux configuration into the clipboard. $ startlog; for cmd in 'uname -a' 'cat /etc/issue' 'dmesg' 'lsusb' 'lspci' 'sudo lshw' 'lsmod'; do log $cmd; done; endlog; printlog | xsel --clipboard This is ready for a trip to http://pastebin.com/, and you don't have to worry about leaving temporary files lying around cluttering up $HOME. Caveats: I'm sure that startlog, endlog, and printlog could use some cleanup and error checking... there are unchecked dependencies between printlog and endlog, as well as between endlog and startlog. It might be useful for 'log' to send stderr to logger as well.

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"

Resample a WAV file with sox
Change the sample rate with sox, the swiss army knife of sound processing.

Get current Xorg resolution via xrandr
Not sure if it works the same on any shell.

New command with the last argument of the previous command.


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