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Stephen Gornick
Asked: 2010-06-01 17:01:44 +0800 CST

Searching for literal "> \" using ack-grep

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I am looking for lines that literally have a greater than character (a ">") followed by a space followed by a backslash character (a "\") i.e., a line with this: > \

I thought escaping would allow this, and for the greater-than it does:

  $ ack-grep "\> "

returns lines that have "> " in them.

But when I try to escape the backslash as well I get:

  $ ack-grep "\> \\"

ack-grep: Invalid regex '\> \':
Trailing \ in regex m/\> /

regex escaping grep

4 Answers

  1. Wow, I was so close ... single quotes:

    $ ack-grep '\> \\'

    Figured this out after confirming that my regex match was valid using: http://regexpal.com/ and just happened to have had single quotes from trying something else.

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  2. This also works:

    $ ack-grep '> \\'

    and so does:

    $ ack-grep "> \\\\"

    The greater-than doesn't need to be escaped.

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  3. To search literal strings, use the literal option:

    ack-grep --literal '> \'
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  4. Please note that the issue here is not with ack but with the shell quoting. You'd have this problem with any program that you were trying to pass in "> \" as an argument.

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