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Creat a tar file for backup info
Use tar command for a backup info with a date of creation

Exclude a string with awk

Hiding password while reading it from keyboard
Allow to read password in a script without showing the password inserted by the user

List files with quotes around each filename

Quick command line math
expr will give you a quick way to do basic math from the CLI. Make sure you escape things like * and leave a space between operators and digits.

Avoids ssh timeouts by sending a keep alive message to the server every 60 seconds
ssh_config is the system-wide configuration file for ssh. For per-user configuration, which allows for different settings for each host: $echo 'ServerAliveInterval 60' >> ~/.ssh/ssh_config On OSX: $echo 'ServerAliveInterval 60' >> ~/.ssh/config or $echo 'ServerAliveInterval 60' >> ~/etc/ssh_config

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"

Create a 5 MB blank file
Useful for testing purposes

Convert a MOV captured from a digital camera to a smaller AVI
Convert those .mov files that your digital camera makes to .avi Adjust the bitrate (-b) to get the appropriate file size. A larger bitrate produces a larger (higher quality) .avi file and smaller bitrate produces a smaller (lower quality) .avi file. Requires ffmpeg (see man page for details) (tested with canon camera MOV files) Other examples: $ffmpeg -i input.mov -sameq -vcodec msmpeg4v2 -acodec pcm_u8 output.avi $ffmpeg -i input.mov -b 1024k -vcodec msmpeg4v2 -acodec pcm_u8 output.avi

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"


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