Shell Programming and Scripting

I'm trying to use regular expression arguments as variables. I have to surround the regular expression with double quotes or else it automatically expands that regular expression to whatever is in that directory.

Unfortunately when I run 'find' it further surrounds the double quotes with single quotes and the regular expression doesn't even get evaluated. I tried removing the double quotes inside the command but once again the regular expression gets expanded. I guess if there was a way to pass the argument only as double quotes without being wrapped in the annoying single quotes would be a fix?

The following should work just fine, since pattern matching does not occur within double quotes:

Code:

re=your_regular_expression
find path -regex "$re"

If this is not what you're trying to do, please clarify with some example code.

Regards,
Alister

I don't know how I can describe the problem without talking all day, especially since this code is proprietary.

Basically the entire ! -regex "regex" as well as possible other ! -regex and ! -name are contained within a single variable, I'm running this on a dir to find non-compliant files for an audit.

For example:

Code:

var="! -regex \"regex\" ! -name path"

Run as:

Code:

find start_path $var -mindepth 1 -maxdepth 1 -type 'd' | ...

Within this variable all the -regex arguments are surrounded in double quotes to prevent them from blowing up, otherwise everything else is left unquoted.

Both the ! and the -regex arguments are getting surrounded in single quotes. I cannot get rid of these single quotes no matter what it seems, Linux puts them there.

Have you tried using eval? It's dangerous if the information is untrusted, but that may not be a concern in this case.

Code:

eval find "$var" -mindepth 1 -maxdepth 1 -type d | ...

It'll probably require backslash quoting exclamation points if the shell supports history expansion.

Regarding the single quotes you're seeing, it sounds like you enabled tracing with set -x.

This example works fine to find all files under the current directory that are not c source:

Code:

$ re_args='\! -regex '\''.*\.c$'\'
$ echo "$re_args"
\! -regex '.*\.c$'
$ eval find . "$re_args" -type f
... <my list of non-C source files here> ...

Regards,
Alister

What if '.*\.c$' is in itself represented by a variable? Surrounding it with single quotes would prevent the variable from being substituted.

Code:

$ re_pattern="'.*\.c\$'"
$ re_args='\! -regex '"$re_pattern"
$ eval find . "$re_args" -type f
... <my list of non-C source files here> ...

Seem to finally be over that pain in the butt, thanks!