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convert from decimal to hexadecimal

Run a command as root, with a delay
$ sleep 1h ; sudo command or $ sudo sleep 1h ; sudo command won't work, because by the time the delay is up, sudo will want your password again.

Generate an XKCD #936 style 4 word passphrase (fast)
Some snippets posted are slow on big dictionaries, this one is fast.

peak amount of memory occupied by any process with "FOO" in its name
Show the maximum amount of memory that was needed by a process at any time. My use case: Having a long-running computation job on $BIG_COMPUTER and judging whether it will also run on $SMALL_COMPUTER.   http://man7.org/linux/man-pages/man5/proc.5.html VmHWM: Peak resident set size ("high water mark")

Create QR codes from a URL.
like 7300, but doesn't clutter your working directory with old qr.*.png files. This will get the QR barcode, and send it right into ImageMagick's 'display' tool. Usage is the same as 7300; just call this function followed by the URL: $ qrurl http://xkcd.com

Fix borked character coding in a tty.
Often you find some tty programs are messed up and confused about character encoding - 'man' is a common problem and sometimes displays weird characters for apostrophes, hyphens etc etc. Another class of programs that suffer from this are those that try to use the line drawing characters - eg RedHat's tty system admin functions such as system-config-firewall-tui system-config-network-tui etc. Adding 'LC_ALL=C' fixes most of these problems (as long as you want English! Perhaps speakers of other languages can add a comment here). For bonus points, I've added the '-c' option to the man command so that it ignores it's cache and re-computes the man page using the C locale.

Place the NUM-th argument of the most recent command on the shell
After executing a command with multiple arguments like cp ./temp/test.sh ~/prog/ifdown.sh you can paste any argument of the previous command to the console, like ls -l ALT+1+. is equivalent to ls -l ./temp/test.sh ALT+0+. stands for command itself ('ls' in this case) Simple ALT+. cycles through last arguments of previous commands.

git diff of files that have been staged ie 'git add'ed

Show the last 20 sessions logged on the machine
change 20 by the number of sessions you want to know (20 it's fair enough)

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" }


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