Forum: Cfengine Help
Subject: Re: Editing only the first line in a file
Author: sauer
Link to topic: https://cfengine.com/forum/read.php?3,21478,21530#msg-21530
Frans Lawaetz Wrote:
-------------------------------------------------------
> There is an "occurrences" option to line edit
> promises.
> cfengine_stdlib.cf has the following:
>
> body replace_with value(x)
> {
> replace_value => "$(x)";
> occurrences => "all";
> }
>
> Try setting it to just "first".
I don't want the first occurance, though - I want to replace it only if it's on
the first line. If, for some reason, someone includes that string later on in
the file (perhaps in a print statement or some in-line documentation), I want
to leave it alone.
The solution I identified does work, albeit slowly (ok,checking 3141 files is
just gonna be slower than setting permissions; it generally takes about 15-20
minutes). Here's the solution I'm ultimately using:
bundle edit_line perl_interpreter {
replace_patterns:
"#!(?!$(perl_path)\s.*U).*perl(?:\s.*)?"
replace_with => value( "#!$(perl_path) -U" ),
select_region => interpreter_line;
}
body select_region interpreter_line {
#select_start => "#!/\S*perl.*";
select_start => ".*";
select_end => "(?!#!).*";
include_start_delimiter => "true";
include_end_delimiter => "false";
}
I changed the select_start to be ".*" in order to suppress the "unable to
sleect a range" messages I get in all of the .pl files which do not have a perl
interpreter at the top, and then changed the replace pattern to use a
zero-width negative lookahead verifying that I don't have the interpreter I
want followed by a capital U (so, for example, /usr/bin/perl -wU is also ok),
and also verifying that I do have a command which has perl followed by either
whitespace or nothing. I suppose that, for maximum flexibility, I should
expand the regex to match any arguments which don't conflict with -U (ie, -T)
and carry those forward. But I'm not going to do that.:)
I'm not entirely sure how setting the include_end_delimiter to false is working
in the case where the first line doesn't have a #!, since the start and end
would potentially both match the same first line - but I don't much care at
this point because I'm not going to edit those files.
On a related note, editing "/path/to/files/.*\.cgi" dissapointingly does not
work; it only edits the last file an "ls *.cgi" would return. :/
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