What is the sh -c command?

The sh -c command is used to run a shell command in a new shell process. The sh command is a shell interpreter that reads and executes commands from a script or from the command line. The -c option is used to specify a command to be executed by the shell.

For example, the following command runs the ls command to list the files in the current directory:

sh -c "ls"

The command is enclosed in quotation marks to ensure that it is interpreted as a single argument by the shell.

You can also use the sh -c command to run multiple commands in a shell script by separating the commands with a semicolon (;). For example:

sh -c "cd /var/log; ls"

This command changes the current directory to /var/log and then lists the files in that directory.

The sh -c command is often used in Upstart scripts to run a shell command as part of the service startup or shutdown process. For example:

pre-start script
    sh -c "mysql -u root -p password < /etc/mysql/init.sql"
end script

In this example, the sh -c command is used to run the mysql command to initialize the database with a script file.

Here are a few additional things to consider when using the sh -c command:

You can use the sh -c command to run a script file by specifying the path to the script file as the command. For example:

sh -c "/path/to/myscript.sh"

This will run the commands in the myscript.sh script file in a new shell process.

You can use the sh -c command to pass arguments to a script file by specifying them after the script file name. For example:

sh -c "/path/to/myscript.sh arg1 arg2"

This will run the myscript.sh script file with the arguments arg1 and arg2.

You can use the sh -c command to run a command with a different shell interpreter by specifying the path to the interpreter as the command. For example:

sh -c "/bin/bash -c 'ls'"

This will run the ls command using the bash shell interpreter.

You can use the sh -c command to set environment variables for the command being run by specifying them before the command. For example:

sh -c "VAR1=value1 VAR2=value2 command"

This will set the VAR1 and VAR2 environment variables to value1 and value2 respectively, and then run the command with these variables set.

I hope this additional information is helpful! Let me know if you have any other questions.

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