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For finding out if something is listening on a port and if so what the daemon is.

date offset calculations
The date command does offset calculations nicely, handles concepts like "a month" as you'd expect, and is good for offsets of at least 100M years in either direction.

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" }

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"

Insert the last argument of the previous command
for example if you did a: $ ls -la /bin/ls then $ ls !$ is equivalent to doing a $ ls /bin/ls

Create/open/use encrypted directory
Create/open/use an encrypted directory encfs needs to be installed During creation easiest to use default values The encrypted files will be in ~/.crypt and you will work as usual in ~/crypt To close the encrypted directory run: fusermount -u ~/crypt When you switch off the computer the encrypted directory will be automatically closed This example uses /home/user/crypt as encrypted directory I use ubuntu linux 8.04 and I am also the creator of www.minihowto.org

Prefix every line with a timestamp
Useful to add a timestamp to every line printed to stdout. You can use `-Ins` instead of `-Iseconds` if you want more precision.

Show the PATH, one directory per line
This is useful for examining the path.

A function to find the newest file in a directory

Extract multiple tar files at once in zsh
tar doesn't support wildcard for unpacking (so you can't use tar -xf *.tar) and it's shorter and simpler than for i in *.tar;do tar -xf $i;done (or even 'for i in *.tar;tar -xf $i' in case of zsh) -i says tar not to stop after first file (EOF)


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