Shell script fails: Syntax error: "(" unexpected

Question

I've been working on a script that automates setting up a development environment for Raspberry Pi development (step by step details that work are here). The script is linked in that article but convenience you can find it here also. Now when run this script install and sets up the environment without error but you have to enter your sudo password more than once due to sudo's time-out value by default. So I started experimenting by removing all the sudo lines and running the whole script via sudo at the command line like so:

kemra102@ubuntuvm:~$ sudo ./pi_dev_env_install.sh

This works fine as expected and gets most of the way through until this point:

./pi_dev_env_install: 68: ./pi_dev_env_install.sh: Syntax error: "(" unexpected

Now this line worked fine previously when not running the whole script with sudo. There is nothing about this line running as sudo that should stop it working to my knowledge, does anyone have any ideas?

Answer 1

The script does not begin with a shebang line, so the system executes it with /bin/sh. On Ubuntu, /bin/sh is dash, a shell designed for fast startup and execution with only standard features. When dash reaches line 68, it sees a syntax error: that parenthesis doesn't mean anything to it in context.

Since dash (like all other shells) is an interpreter, it won't complain until the execution reaches the problematic line. So even if the script successfully started at some point in your testing, it would have aborted once line 68 was reached.

The shebang line must be the very first thing in the file. Since you use bash features, the first line of the file must be #!/bin/bash or #!/usr/bin/env bash.

Answer 2

For me starting script with:

bash ./< script file > 

works fine.

Answer 3

If the shebang is not on the first line, it will not be respected, regardless of the shell of the root user, the SHELL variable or the -s flag. You can easily confirm this is with a simple example:

#
#!/bin/bash
offset=(`ls`)
echo $offset

Running this script with sudo will raise a syntax error in recent versions of Ubuntu and Debian.

You have two options to make sure the script is interpreted by bash:

1. Move the shebang to the first line

2. Run sudo like this:

    sudo bash ./pi_dev_env_install.sh
   

Answer 4

This can happen if you override the intended interpreter. E.g this will run with sh regardless of what hash bang is used (handy when not using hash bang):

> sh run.sh

OR to run bash:

> bash run.sh

To let it use the script defined hash bang value, use this:

> ./run.sh

Answer 5

Try dos2unix in script file. Sometimes some hidden characters are there in the source.

command:

dos2unix script_file.sh script_file.sh

Answer 6

Maybe you have a "(" on the dir or file name.

Answer 7

sudo chmod 755 <script>

In my case the error was lack of permissions to execute the file. Only got the error message when I separated the commands:

$ sudo sh
# ./install