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Find out what package some command belongs to (on RPM systems)
Replace 'more' command with any command which is in your PATH.

ps with parent/child process tree
Shows a tree view of parent to child processes in the output of ps (linux). Similar output can be achieved with pstree (also linux) or ptree (Solaris).

Encrypt every file in the current directory with 256-bit AES, retaining the original.
The password is stored in the password file, which obviously must be kept secure, encrypted later with gpg, deleted, or whatever you prefer. To decrypt: $ openssl enc -d -aes-256-cbc -salt -in filename.enc -out filename -pass file:/path/to/password-file Alternative ciphers can be used, of course.

Find all files with root SUID or SGID executables
Discovering all executables on your system that can be run as another user, especially root, is critical for system security. The above command will find those files with have SUID or SGID bits set and are owned by the root user or group.

List the number and type of active network connections

ROT13 using the tr command

Translate your terminal into Swedish Chef
Bork, bork, bork! To keep it short, the first terminal line doesn't show a prompt.

Number of .... indicate how far down to cd
Use dots to cd down directories instead of having to remember all of the pesky back slashes! Better yet, works on even and odd number of dots! Now, just estimate how far down you want to traverse.

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" }

Convert seconds into minutes and seconds
This is a very simple way to input a large number of seconds and get a more useful value in minutes and seconds. Avoids useless use of echo.


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