Executing a list of commands on distinct lines with bash -c?

Question

I pass a list of commands to a bash script through an environment variable as shown in the example below:

CMDS=' date > date.txt cat date.txt date | rev ' script

What is the correct way to execute these commands in the bash script ?

I did the following and it seams to work. Is it correct ?

#! /bin/bash bash -c "$CMDS"

As long as the string CMDS is not using another ' it should be correct. Example for a problematic CMDS string would be: CMDS='echo "hello world"; echo ';echo $0'; echo "good bye"'. — paladin
– paladin, Commented Jan 18, 2024 at 11:23
@paladin thank you very much. Is there a way to avoid this limitation ? I use this to filter forced commands in ssh authorized_keys file. I use a script that only accepts to execute commands listed in a file in the remote host. — chmike
– chmike, Commented Jan 19, 2024 at 12:26
Use " instead of ' and escape everything which is problematic, like so: CMDS="echo \"hello world\"; echo ';echo \$0'; echo \"good bye\"". — paladin
– paladin, Commented Jan 19, 2024 at 12:41

Robert Glonek · Accepted Answer · 2024-06-17 04:24:34Z

While it is correct, as long as you escape any single quotes in the CMDS with a single backslash, why not put the commands in a function instead?

function bob() { command1 command2 command3 } bob

You can even pass arguments and read return codes.

function bob() { echo $1 echo $2 return 5 } bob param1 param2 echo $?

Using functions avoids calling a new instance of bash shell to run the commands.

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