Colon used after the equal sign in a shell script

Question

The following is taken from the GNU ld configure file:

if test $ac_verc_fail = yes; then 
  LD=: critic_missing="$critic_missing ld"
fi

What's the meaning of the colon?

score 1 · Answer 1 · edited May 23 '17 at 11:50

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The : is a shell builtin that is basically equivalent to the true command. It is often used as a no-op, e.g. after an if statement. Please see this excellent reply by @earl for more information.

Best regards //KH.

edited May 23 '17 at 11:50

Community

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answered Mar 10 '14 at 08:02

Karl-Henrik

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I had in fact read the link before I posted the question. What's misleading is the two clauses being put in a single line without a semicolon between them. I had never done that before. – duleshi Mar 10 '14 at 08:22
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In `LD=:`, colon is not a builtin, it is just a value assigned to a variable. – choroba Mar 10 '14 at 09:10

score 0 · Answer 2 · answered Mar 10 '14 at 09:19

I propose an alternative : I believe it could be a typo ...

It could be meant to be:

LD=; critic_missing="$critic_missing ld"

which is equivalent to (but less readable than):

LD="" ; critic_missing="$critic_missing ld"

That would fit better with the following statement critic_missing="$critic_missing_ld" ?

(whereas in your post ld is not realling missing, it's set to ":")

Colon used after the equal sign in a shell script

2 Answers2