Syntax error near =~ operator

Question

When I run this script:

#!/bin/bash

if [[ "abcd" =~ ^.*$ ]]; then
    echo "something"
fi

I get:

./tmp2.sh: line 3: conditional binary operator expected
./tmp2.sh: line 3: syntax error near `=~'
./tmp2.sh: line 3: `if [[ "abcd" =~ ^.*$ ]]; then'

I've tried all suggestions I've found, but still the same:/ Help me, please!

[I've failed to reproduce this behaviour.](http://ideone.com/n22r76) — Unihedron, Jul 12 '14 at 14:37
How are you running the script? Are you sure the script is being run by `bash`, not some other shell or `bash` in POSIX mode? — chepner, Jul 12 '14 at 15:16

score 6 · Accepted Answer · answered Jul 12 '14 at 17:06

6

Given that you're seeing a bash-specific error message, we can rule out that something other than bash is running the script (if it were a POSIX-features-only shell, such as sh on some systems, you'd instead see an error message relating to [[).

The most likely explanation:

Your bash version is < 3.0, and therefore doesn't support the =~ operator.
- To verify, run echo $BASH_VERSION in your script.

The specific error you're seeing is bash's way of saying: "I'm seeing a string I don't recognize as an operator."

answered Jul 12 '14 at 17:06

mklement0

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You got it right. I should have checked earlier versions too. – konsolebox Jul 12 '14 at 17:08
Sounds likely, but concerning how horribly outdated OP's system is. Bash 3 turns 10 in a couple weeks. – Kevin Jul 12 '14 at 17:17

score 3 · Answer 2 · answered Jul 12 '14 at 16:48

3

Run your script with bash script.sh not sh script.sh. It probably would also work with ./script.sh if script.sh is already executable since you're using the header #!/bin/bash.

answered Jul 12 '14 at 16:48

konsolebox

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Bad_Coder · Answer 3 · 2014-07-12T15:47:36.137

1

this should work

re='^.*$'
if [[ "abcd" =~ $re ]]; then
  echo "something"
fi

edited Jul 12 '14 at 15:47

answered Jul 12 '14 at 14:30

Bad_Coder

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1

It would be helpful to explain the syntax. Please expand on your answer. – David Brossard Jul 12 '14 at 15:02
3

This wouldn't help. The `=~` syntax works in all versions of Bash starting 3.0. – konsolebox Jul 12 '14 at 16:44
While storing your regex in an auxiliary variable does help in some situations (with regexes that contain `\ `-prefixed sequences such as `\<` or `\s`), this is NOT the problem here - yours an the OP's code are equivalent. – mklement0 Jul 12 '14 at 19:31

score 0 · Answer 4 · answered May 11 '20 at 16:27

0

This is almost identical to the error you get in all versions of bash that support regex if you put ~= rather than =~.

answered May 11 '20 at 16:27

Martin

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How is this answering the question? – Toto May 11 '20 at 16:32
Because I came here from google trying to investigate why I was getting "conditional binary operator expected" and it wasn't until I copied the example from here did I spot the obvious error. It looks almost identical to the error listed above and I have spent quite a while searching for this resolution. If you are on this page with that error and you haven't checked the =~ it is probably a far more common reason it's not working. – Martin May 11 '20 at 16:36
May be, but this doesn't answer actual question and shouldn't be here, SO is not a forum. – Toto May 11 '20 at 17:26
1

When you google "stack overflow" "syntax error near" "~=", this page is top of the list. It is not immediately obvious that google has swapped the =~ for you. This post answers that related question. – Martin May 12 '20 at 09:29

Syntax error near =~ operator

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