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Backup a file with a date-time stamp
Appends the input file with the date format YYYY-MM-DD.bak. Also runs silently if you remove the -v on the cp at the end of the function.

Remount an already-mounted filesystem without unmounting it
Necessary for fsck for example. The remount functionality follows the standard way how the mount command works with options from fstab. It means the mount command doesn't read fstab (or mtab) only when a device and dir are fully specified. After this call all old mount options are replaced and arbitrary stuff from fstab is ignored, except the loop= option which is internally generated and maintained by the mount command. It does not change device or mount point.

Get size of terminal
See the cols and lines and make sure the console it correctly configured for the screen size.

autorun program when logon Windows XP

Block all IP addresses and domains that have attempted brute force SSH login to computer
I use iptables. To rate limit connections. Very easy and no ban lists to manage.

password generator
make password randomly, default 8 chars, using bash3.X only, no external program.

Substitute an already running command
eg: Already running cmd $sleep 120 Substitution cmd $c=$(pgrep sleep) && sleep 5 && kill $c

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" }

calculate in commandline with bash
Only works for integer arithmetic.

Sprunge.us - CLI alternative to PasteBin.com
NAME sprunge: command line pastebin: SYNOPSIS | curl -F 'sprunge=


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