Bash script help

[ykumar6]

I have a bash script that looks like this

bash ./start.sh > ../logs/stdout.log 2> ../logs/stderr.log &
STARTED=$!
echo "$STARTED" >> ../run.pid
wait $STARTED

What does the "&" after ../logs/stderr.log do?
Also, why do I need to put "bash" infront of "./start.sh"

Thanks!

[scathefire]

What does the "&" after ../logs/stderr.log do?

It puts the start.sh script that executed into the background.

[atreyu]

Also, why do I need to put "bash" infront of "./start.sh"

If the script is not executable, or if it does not have the command line interpreter (bash, in this case) defined in the script, it needs to know how to run it.

To see if it is executable, you can do:

ls -l start.sh

In the below output, the three x's mean the script is executable by owner, group, and all:

-rwxr-xr-x  1 root root  243  Dec 1 2011 myscript.sh

Assuming you have permissions to do it, you can make a script executable with:

chmod +x start.sh

The command line interpreter is probably already defined at the top of the script. For example, a script's command line interpreter could look like one of:

#!/bin/sh

#!/bin/bash

#!/usr/bin/env sh

#!/usr/bin/perl

The first two would try to execute the script using bash (or sh, which usually is a symlink to bash) located in the /bin dir. The third will look in your PATH for sh (which is smarter than hard-coding it to /bin), and the 4th will use perl.