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Fast file backup
This is a BASH feature. The above command will create a backup of "filename" called "filename.DATE", where DATE is the actual day in %Y%m%d (year, month and day numbers together) format.

Print a horizontal line

Command for JOHN CONS
Would create a file with a meaningful title. Dedicated to John Cons, who is annoying us users. Merry Christmas!!!

add a ip address to a network device
Allows to add more than one ip address to one network device.

check open ports (both ipv4 and ipv6)

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" }

Prevent non-root users from logging in
Also with optional message: $ echo "no login for you" > /etc/nologin (This doesn't affect your current X session - you're already logged in!)

Save the list of all available commands in your box to a file
When you press TAB twice in your prompt, bash tells you something like "Display all 4567 possibilities? (y or n)" But when you press "y" you only get the list in the terminal output and, if you want to save it to a file, you have to copy it by hand from the vterm screen. With this utility you save the list to a file or pipe it to another command at will You can use the file saved list to grep for a particular pattern, useful if you are searching for a command but you only remember a few letters

Reduce PDF size

get the top 10 longest filenames


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