Commands using gawk (36)

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Show numerical values for each of the 256 colors in ZSH
This will show a numerical value for each of the 256 colors in ZSH. Everything in the command is a ZSH builtin, so it should run on any platform where ZSH is installed. Prints one color per line. If someone is interested in formatting the output, paste the alternative.

cp the file
Copy the file with the given .extension at the source file's location. Eliminates the typing of long paths again and again.

Define shell variable HISTIGNORE so that comments (lines starting with #) appear in shell history
I was surprised to find that with RedHat bash, I could not find any comment lines (begining with #) in my bash shell history. Surprised because in Mageia Linux this works. It turns out that RedHat's bash will keep comment lines if in my .bashrc, I define: export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' Why have comment lines in shell history? It's a handy and convenient way to make proto-commands (to be completed later) and for storing brief text data that is searchable in shell history.

Terminal redirection
can display the commands and their output to another user who is connected to another terminal, by example pts/3

Find total Terabytes written to a SSD
You must have smartmontools installed for this to work. This also assumes you 512 byte sector sizes, this is pretty standard.

clean up memory of unnecessary things (Kernerl 2.6.16 or newer)
run sync first to flush useful things out to disk!!! To free pagecache: echo 1 > /proc/sys/vm/drop_caches To free dentries and inodes: echo 2 > /proc/sys/vm/drop_caches To free pagecache, dentries and inodes: echo 3 > /proc/sys/vm/drop_caches

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.

validate xml in a shell script using xmllint

save date and time for each command in history
Date-time format: YYYY-MM-DD HH:MM:SS

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"


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