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How can I execute a group of commands as another user in Bash?

Tags:

bash

su

There are already some existing questions asked here about running commands as another user. However, the question and answers focus on a single command instead of a long group of commands.

For example, consider the following script:

#!/bin/bash
set -e

root_command -p param1  # run as root

# these commands must be run as another user
command1 -p 'parameter with "quotes" inline'
command2 -p 'parameter with "quotes" inline'
command3 -p 'parameter with "quotes" inline'

There are a couple of important points to note here:

  • The final three commands must be run as another user using su or sudo. In the example there were three commands, but suppose that there were many more...

  • The commands themselves make use of single and double quotes.

The second point above prevents the use of the following syntax:

su somebody -c "command"

...since the commands themselves contain quotes.

What is the proper way to "group" the commands and run them under another user account?

like image 893
Nathan Osman Avatar asked Jul 20 '13 03:07

Nathan Osman


2 Answers

Try this:

su somebody <<'EOF'
command1 -p 'parameter with "quotes" inline'
command2 -p 'parameter with "quotes" inline'
command3 -p 'parameter with "quotes" inline'
EOF

<< introduces a here-doc. The next token is the delimiter, and everything up to a line beginning with the delimiter is fed as standard input to the command. Putting the delimiter in single quotes prevents variable substitution within the here-doc.

like image 151
Barmar Avatar answered Oct 22 '22 17:10

Barmar


I'm not that great with Bash-foo, so there is bound to be a more elegant way, but I've approached this problem in the past by using multiple scripts and a "driver".

E.g.,

Driver

#!/bin/bash
set -e

su root script1
su somebody script2

Script1

#!/bin/bash
set -e

root_command -p param1  # Run as root

Script2

#!/bin/bash
set -e

# These commands must be run as another user
command1 -p 'parameter with "quotes" inline'
command2 -p 'parameter with "quotes" inline'
command3 -p 'parameter with "quotes" inline'
like image 20
stefancarlton Avatar answered Oct 22 '22 17:10

stefancarlton