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Detect encoding of a text file
This command gives you the charset of a text file, which would be handy if you have no idea of the encoding.

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

Check every URL redirect (HTTP status codes 301/302) with curl
curl -sLkIv --stderr - https://t.co/2rQjHfptZ8 -s: silences the output when piped to a different command -L: follow every redirect -k: ignores certificate errors -I: just request the headers -v: be verbose --stderr - : redirect stderr to stdout https://t.co/2rQjHfptZ8: URL to check for redirects piped to grep -i location: -i: grep target text ignoring case location: : greps every string containing "location:" piped to awk {'print $3'} prints the third column in every string piped to sed '/^$/d' removes blank lines

List just the executable files (or directories) in current directory
Does an 'ls' on just the files and directories in the current directory with an execute bit turned on. This version will list directories. Just tack on "-type f" to the start of the find to omit listing directories and list only files.

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" }

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" }

Convert PNG to GIF
(relies on 'imagemagick') Convert all .png files to .gif. This can also go the other way if you reverse the file extensions in the command, e.g.: $ for file in *.gif; do convert "$file" "$(basename $file .gif).png"; done If the file is named 'example1.png' it will be named 'example1.gif' when it is complete.

Download SSL/TLS pem format cert from https web host

Restart command if it dies.
works well in crontab.

Lists all listening ports together with the PID of the associated process
Lists all opened sockets (not only listeners), no DNS resolution (so it's fast), the process id and the user holding the socket. Previous samples were limiting to TCP too, this also lists UDP listeners.


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