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Accepted
Nick Weavers
Asked: 2020-01-24 15:53:46 +0800 CST

Why can I update a file owned by root using sudo vi, but not append a line to it with sudo echo "Thing" >> file?

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I would like to have script that is doing automated migrations of websites from another be able to append Includes to the /etc/httpd/conf.d/vhosts.conf file.

However, when I try to use echo to put append a string to the end of the file I get this:

$ sudo echo "Include thing" >> /etc/httpd/conf.d/vhosts.conf
-bash: /etc/httpd/conf.d/vhosts.conf: Permission denied

and yet I can vi /etc/httpd/conf.d/vhosts.conf, add the line and :wq the file to save and close it.

What am I missing?

sudo file-permissions redirection

1 Answers

  1. Best Answer

    Sudo elevates the process it calls, it does not elevate any of the current shell's processing like redirection, globbing, etc.

    The file redirection >> /etc/httpd/conf.d/vhosts.conf is being processed by your current shell, which is still running under your current privileges.

    You could try something like this.

    sudo bash -c 'echo "Include thing" >> /etc/httpd/conf.d/vhosts.conf'

    Or 

    echo "Include thing" | sudo tee -a /etc/httpd/conf.d/vhosts.conf
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