How to append to a file as sudo?

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I want to do:

echo "something" >> /etc/config_file

But, since only the root user has write permission to this file, I can’t do that. But the following also doesn’t work.

sudo echo "something" >> /etc/config_file

Is there a way to append to a file in that situation without having to first open it with a sudo‘d editor and then appending the new content by hand?

Answer

Use tee -a (or tee --append) with sudo

tee - read from standard input and write to standard output and files
[...]
   -a, --append
      append to the given FILEs, do not overwrite
[...]

So your command becomes

echo "something" | sudo tee -a /etc/config_file

The advantages of tee over executing Bash with administrative permissions are

  • You do not execute Bash with administrative permissions
  • Only the ‘write to file’ part runs with advanced permissions
  • Quoting of a complex command is much easier

Attribution
Source : Link , Question Author : agentofuser , Answer Author : Boris

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