[Linux](EN) Ignore stderr in terminal prompt using /dev/null and redirect

Redirect stderr to /dev/null so that ignore prints of standard errors in terminal prompt.

Environment and Prerequisite

• Linux base system
• Bash shell(/bin/bash)
• Redirect

Terms

What is /dev/null?

• /dev/null: Device file that discards all data written to it but reports that the write operation succeeded.
• You can ignore standard error on screen when you write stderr to /dev/null.

What is redirect?

• Redirect('>'): Redirect standard streams to user-specified locations like file or other stream.
• Reference: Redirection (computing)

Usage example

Ignore stderr in find command

• It prints Permission denied as stderr

$ find / | grep neutron
find: ‘/run/docker’: Permission denied
find: ‘/run/containerd’: Permission denied
find: ‘/run/lxcfs’: Permission denied
find: ‘/run/sudo’: Permission denied
find: ‘/run/log/journal/50739525d1fb4eac9e863478fb990fed’: Permission denied
find: ‘/run/lvm’: Permission denied

• After redirect stderr to /dev/null, there is no Permission denied
• 2 represents stderr

find / 2> /dev/null | grep neutron
/home/twpower/test/neutron_patched
/home/twpower/test/neutron_patched/LICENSE
/home/twpower/test/neutron_patched/.gitignore
/home/twpower/test/neutron_patched/bin
...

Reference

• https://en.wikipedia.org/wiki/Null_device
• http://linuxcommand.org/lc3_man_pages/grep1.html
• https://en.wikipedia.org/wiki/Redirection_(computing)