Shell Knowledge

• Spawn a TTY using Python
• Manually generate a crypt (/etc/shadow) password
• Get total duration of video files
• Iterate over lines in a file or a command
• Unique files using AWK

Spawn a TTY using Python

Spawn a “real” TTY. Useful for sudo, su, ssh…

python -c 'import pty; pty.spawn("/bin/sh")'

Manually generate a crypt (/etc/shadow) password

Generate a UNIX crypt password with a given salt and password

openssl passwd -1 -salt <SALT> <PASSWORD>

# openssl passwd -1 -salt salty bacon
$1$salty$OxTbIoRN3a6XyEn362VfU0

Found here

Get total duration of video files

Get the total duration of video files in a directory.

exiftool -n -q -p '${Duration;our $sum;$_=ConvertDuration($sum+=$_)}' */*.mp4 | tail -n1

Found here

Iterate over lines in a file or a command

Execute any command on every single line of a given file.

while read p; do
    echo $p;
done < file

This may be used also on multi-line spaced outputs.

find S0* | while read p; do
    echo $p;
done

Unique files using AWK

For a given file, print unique lines, even if the file is not sorted (unlike uniq). High memory use for big files!

awk '!a[$0]++' FILE