CODEWITHSUNDEEP
bashshellshebang
Rob Sweet
Rob Sweet

Reputation: 184

What does Hash Colon (#:) mean as first line of shell script?

I have inherited a number of shell scripts on a Centos system which start with #: on the first line.

#:

DATE=`date +%D::%H:%M`
LOG=/home/alert/bin/log/test.log

echo ${DATE} >> ${LOG}

exit

What does #: mean?

I know what a 'normal' shebang means such as #!/bin/sh

I have looked all over the internet and stack overflow and haven't found an answer. I'm guessing it means "use your shell"? (ie., #!$SHELL)?

FYI - There is one other question/answer regarding #: imbedded in shell scripts where #: is a type of comment that is included in man files. In this instance, it does not appear to apply given that this comment only appears on the first line of the file and does not have any following text.

Upvotes: 2

Views: 586

Answers (1)

Mark Reed
Mark Reed

Reputation: 95242

Good question. It is not treated as a shebang; the script appears to run the same way any other script with no shebang is run by the shell: it shows up in ps as bash -himBH rather than bash filename. As far as I can tell, it's just a comment.

It might be the old "hey, this is a shell script!" syntax from before interpreter support via #! was added to the exec system call: scripts that started with #: - actually, probably just # or : would work - would be recognized as such by the shell itself and executed by it directly rather than by calling exec. I can't think of a reason for it on a modern system, though.

Upvotes: 4

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