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Creates a 'path' command that always prints the full path to any file
The command creates an alias called 'path', so it's useful to add it to your .profile or .bash_profile. The path command then prints the full path of any file, directory, or list of files given. Soft links will be resolved to their true location. This is especially useful if you use scp often to copy files across systems. Now rather then using pwd to get a directory, and then doing a separate cut and paste to get a file's name, you can just type 'path file' and get the full path in one operation.

Disable the ping response
It really disables all ICMP responses not only the ping one. If you want to enable it you can use: $ sudo -s "echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all"

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" }

Plaintext credentials sniffing with tcpdump and grep
Simple TCPDUMP grepping for common unsafe protocols (HTTP, POP3, SMTP, FTP)

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"

Backup files older than 1 day on /home/dir, gzip them, moving old file to a dated file.
Useful for backing up old files, custom logs, etc. via a cronjob.

Display list of available printers

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"

processes per user counter
enumerates the number of processes for each user. ps BSD format is used here , for standard Unix format use : ps -eLf |awk '{$1} {++P[$1]} END {for(a in P) if (a !="UID") print a,P[a]}'

Combine multiple images into a video using ffmpeg
The -start_number can be ignored if sequence starts with 0, otherwise use first number in sequence


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