. "$1"

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

All hail ye PerlMonk Gods ... May I be so bold as to put forth a question seeking knowledge?

What does

. "$1"

mean when it is the first line in a perl script?

I would guess it means this:

$_ = $_ . "$1"

where $_ is the default perl variable

and

$1 is the match/capture group 1

But, that makes no sense as the first line. So, what gives?

Thanks in advance!

Comment on . "$1"

Replies are listed 'Best First'.
Re: . "$1" by bliako (Abbot) on Aug 24, 2018 at 00:28 UTC
You assumed the file contains Perl code. Are you sure? I mean are there more lines further down to look and smell like Perl? In a unix shell like `sh` or `bash` (and possibly others) the `.` (the dot) is an alias for `source` which executes the contents of a file in the current shell using the current shell as the interpreter. While `$1` is the first argument to the command. So, `. "$1"` in `sh/bash` means `source` the file named by the first argument of this command. And the quotes will make it immune to spaces in the filename. example: xx.sh: `# file xx.sh # allegedly perl script . "$1"` [download] yy.sh: `# yy.sh a sh script to be executed echo "hello there i am calling from within yy.sh"` [download] and in a shell: `$ chmod 755 xx.sh $ xx.sh yy.sh hello there i am calling from within yy.sh` [download] bw, blako	[reply] [d/l] [select]
Re: . "$1" by hippo (Archbishop) on Aug 24, 2018 at 08:10 UTC
Try it and see: `$ perl -e '. "$1"' syntax error at -e line 1, near "." Execution of -e aborted due to compilation errors.` [download] So, as everyone else has hinted, it isn't valid Perl.	[reply] [d/l]
Re: . "$1" (updated) by AnomalousMonk (Archbishop) on Aug 23, 2018 at 23:29 UTC
What does . "$1"* mean when it is the first line in a perl script?* If that's really absolutely all there is on the first line, it means the file containing the script has been corrupted; characters have been lost off of the beginning (at least!) of the file. (Update: Of course, this assumes the script is (or was) Perl to begin with. Others have suggested this code fragment is a piece of a shell script, and this seems much more likely to be the answer!) Give a man a fish: `<%-{-{-{-<`	[reply] [d/l]
Re: . "$1" by LanX (Saint) on Aug 23, 2018 at 22:45 UTC
Looks like a syntax error for me. This compiles? The only way to make this work might be a code transforming option from `perlrun` Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply]