What is wrong with this bash scripting syntax for adding an element to an array?

Question

A simple shell script used for creating some system reporting contains the code

ARRAY=$(awk -F ':' '$3>=1000 && $3<60000 {print $1}' /etc/passwd)
ARRAY+=('root')

The array's declaration in the first line doesn't produce any error output, but for the second line I get an error message saying: Syntax error: word unexpected (expecting ")")

What is wrong with this code?

What is your bash version? The first line does not mean you are working with an array, $(..) is a command substitution syntax. Either way it should not produce the error you said — Inian
– Inian, Commented Jun 18, 2017 at 10:27
Use: ARRAY=($(awk -F ':' '$3>=1000 && $3<60000 {print $1}' /etc/passwd)) — Cyrus
– Cyrus, Commented Jun 18, 2017 at 10:31
Éxactly, it should work like Cyrus wrote. However, I then get this error for the initial array initialization: Syntax error: "(" unexpected - And if I leave out the outer brackets (s. above), the array gets initialized, but then the second line produces this totally obscure error. My bash version is 4.3.30. — c128linux
– c128linux, Commented Jun 18, 2017 at 10:38
I demonstrated this odd behavior and took a screenshot of it, which you can view here: Weird bash behavior — c128linux
– c128linux, Commented Jun 18, 2017 at 10:46

Eric Renouf · Accepted Answer · 2017-06-18 11:06:16Z

3

The problem, from your screenshot, is that you are not running it as a bash script. You're doing sh testscript which executes it with the sh shell, which is not bash. Make the changes that @Cyrus recommended and either make the script executable so you use the shebang line and do ./testscript or use bash to run it bash testscript

Also, set +x turns off tracing/debugging so when you're hitting unexpected problems you'd be better using set -x to turn it on for the block in question.

I demonstrated the problem for myself as follows:

$ cat testscript
ARRAY=$(awk -F ':' '$3>=1000 && $3<60000 {print $1}' /etc/passwd)
ARRAY+=('root')
$ sh testscript
testscript: 2: testscript: Syntax error: word unexpected (expecting ")"
$ bash testscript
$

edited Jun 18, 2017 at 11:06

answered Jun 18, 2017 at 10:56

Eric Renouf

14.6k3 gold badges53 silver badges73 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

c128linux Over a year ago

Thanks a lot for your answer, it now indeed behaves in the way I would have expected it to behave. Still I really wonder why sh (after having initialized the array successfully with the right values when leaving out the outer brackets) produces this (to me) totally weird syntax error for ARRAY+=('root') - Why does it expect a closing bracket in this line, although there already is an opening and a closing bracket?

Eric Renouf Over a year ago

@c128linux It seems to be treating the line as though it's doing name() to define a function, in this case it would be named ARRAY+=. There's an unexpected word in the middle of the parens though. If you take 'root' out it will then complain about an illegal function name

c128linux Over a year ago

Thanks for this in-depth explanation! @Cyrus Answer accepted ;)

Collectives™ on Stack Overflow

What is wrong with this bash scripting syntax for adding an element to an array?

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related