Construct perl command params from the command line

Question

I would like to add multiple -e command dynamically to perl but it throws multiple errors like this:

String found where operator expected at -e line 2, near "'s/\$testName/\$test-name/g;'" (Missing semicolon on previous line?)

Heres what I'm doing:

find css -name "*.scss" -print0 | \
xargs -0 -t perl -pi \
$(perl -ne '/^(\$(?=[a-z0-9]*[A-Z])[^:\s]+)\s*:/ && print "-e \047s/\\$1/\\" . lc(join("-", split(/(?=[A-Z])/, $1))) . "/g;\047\n"' _variables.scss | sort -ur | tr "\n" " ")

The command $(perl -ne ...) extracts and transforms some content and outputs something like:

-e 's/\$testName/\$test-name/g;' -e 's/\$coolName/\$cool-name/g;' -e 's/\$camelCased/\$camel-cased/g;'

As far as I can tell the problem resides in the way bash/perl evaluates the last command, the manual execution of the command output by "xargs -t" works fine.

The following simple case fails too:

target="-e 's/\$testName/\$test-name/g;' -e 's/\$coolName/\$cool-name/g;' 's/\$camelCased/\$camel-cased/g;'"
perl -pi $target css/core.scss

Where do you pass the arguments produced by xargs, to the outer perl or the inner one? — konsolebox
– konsolebox, Commented Aug 4, 2014 at 16:29
To the outer perl: "search and replace all pairs provided by the inner perl". — luissquall
– luissquall, Commented Aug 4, 2014 at 16:59
You don't get quote removal on the results of variable expansion and command substituion. See mywiki.wooledge.org/BashFAQ/050 . — Etan Reisner
– Etan Reisner, Commented Aug 4, 2014 at 17:00

konsolebox · Accepted Answer · 2014-08-04 17:35:41Z

1

Try this:

ARGS=$(perl -ne '/^(\$(?=[a-z0-9]*[A-Z])[^:\s]+)\s*:/ && print "-e \047s/\\$1/\\" . lc(join("-", split(/(?=[A-Z])/, $1))) . "/g;\047\n"' _variables.scss | sort -ur | tr "\n" " ")
eval "find css -name '*.scss' -print0 | xargs -0 -t perl -pi $ARGS"

Or

eval "find css -name '*.scss' -print0 | xargs -0 -t perl -pi $(perl -ne '/^(\$(?=[a-z0-9]*[A-Z])[^:\s]+)\s*:/ && print "-e \047s/\\$1/\\" . lc(join("-", split(/(?=[A-Z])/, $1))) . "/g;\047\n"' _variables.scss | sort -ur | tr "\n" " ")"

edited Aug 4, 2014 at 17:35

answered Aug 4, 2014 at 17:05

konsolebox

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1 Comment

luissquall Over a year ago

It works great, is it possible to make it work without the ARGS var? Something similar to @mr-llama suggestion: "find ... | xargs -0 -t eval..."?

Mr. Llama · Accepted Answer · 2014-08-04 16:59:22Z

0

You'll need to include an eval with the xargs to get the variable to be parsed as parameters. Here's a quick demonstration:

# Variable containing parameters
> target="-e 's/a/b/g;' -e 's/x/y/g;'"

# Variable substitution - Doesn't work
> echo "aaaabbbbccccddddxxxx" | perl -pi ${target}
String found where operator expected at -e line 2, near "'s/x/y/g;'"
        (Missing semicolon on previous line?)
syntax error at -e line 2, near "'s/x/y/g;'"
Execution of -e aborted due to compilation errors.

# Manual substitution - Works
> echo "aaaabbbbccccddddxxxx" | perl -pi -e 's/a/b/g;' -e 's/x/y/g;'
bbbbbbbbccccddddyyyy

# Eval substitution - Works
> echo "aaaabbbbccccddddxxxx" | eval perl -pi ${target}
bbbbbbbbccccddddyyyy

In your situation, the following should work:

find css -name "*.scss" -print0 | \
    xargs -0 -t eval perl -pi $(perl -ne .....)

answered Aug 4, 2014 at 16:59

Mr. Llama

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luissquall Over a year ago

Thank you @Mr. Llama. I couldn't make it work with eval and xargs. I got this error: "xargs: eval: No such file or directory".

Etan Reisner · Accepted Answer · 2014-08-04 17:01:34Z

0

You don't get quote removal on the results of variable expansion and command substituion.

See http://mywiki.wooledge.org/BashFAQ/050 for more details.

You can't get what you want here the way you are trying to do it. Store the results of the inner perl in an array and expand that on the outer perl command.

answered Aug 4, 2014 at 17:01

Etan Reisner

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