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IBM AIX: Extract a .tar.gz archive in one shot

Generate a Random MAC address
Use the following variation for FreeBSD: $ openssl rand 6 | xxd -p | sed 's/\(..\)/\1:/g; s/:$//'

Find files that are older than x days
Find files that are older than x days in the working directory and list them. This will recurse all the sub-directories inside the working directory. By changing the value for -mtime, you can adjust the time and by replacing the ls command with, say, rm, you can remove those files if you wish to.

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"

Short one line while loop that outputs parameterized content from one file to another
There is a common command for outputting a field or list of fields from each line in a file. Why wouldn't you just use cut?

Remove the first character of each line in a file

run command on a group of nodes in parallel

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" }

Go to parent directory of filename edited in last command

Remove orphaned dependencies on Arch
-Qdt Lists dependencies/packages which are no longer required by any packages -q Output only package name (not the version number) -R Remove package(s) Rest is self-explanatory. I just started out with Arch - so if there is any better/standard method to achieve the same - please suggest.


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