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display a smiling smiley if the command succeeded and a sad smiley if the command failed
you could save the code between if and fi to a shell script named smiley.sh with the first argument as and then do a smiley.sh to see if the command succeeded. a bit needless but who cares ;)

encode HTML entities
Encodes HTML entities from input (file or stdin) so it's possible to directly past the result to a blog or HTML source file.

Simple complete system backup excluding files or directories
You can exclude more system folders or individual files which are not necessary for the backup and can be recreated after the restore procedure, like /lost+found, /mnt, /media, /tmp, /usr ... Restoring the above backup procedure is as simple as becoming root and typing: $ tar zxpf backup.tgz -C / You can extract any file or directory out of the backup.tgz file for recovery, for instance, if you have a corrupt or mis-configured fstab file, you could simply issue the command: $ tar zxpf backup.tgz /ect/fstab -C / Other options: v add verbose option to see files processed A far safer solution is to restore the desired files under a different directory, and then compare, move, or update the files to their original locations afterward.

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.

Configure a serial line device so you can evaluate it with a shell script
I had a hard time in finding the correct settings to get reasonable output from a coin selector which sends its data over a serial line. In the end, minicom came to the rescue and pointed me on the right track. So, if you need to do something similar, these settings may help you. Replace ttyUSB0 with your device file, 9600 with your baud rate, 5 with your read timeout (10ths of a second), and 1 with the minimum numbers of characters you want to read. You can then open the device file like you are used to do, example: $ DATA="`xxd -ps -l 5 \"$DEV\"`"

Find broken symlinks

Detect illegal access to kernel space, potentially useful for Meltdown detection
Based on capsule8 agent examples, not rigorously tested

Read random news on the internet
sort -R randomize the list. head -n1 takes the first.

Shows size of dirs and files, hidden or not, sorted.

Recursively grep for string and format output for vi(m)
This is a big time saver for me. I often grep source code and need to edit the findings. A single highlight of the mouse and middle mouse click (in gnome terminal) and I'm editing the exact line I just found. The color highlighting helps interpret the data.


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