How to escape parenthesis in egrep

Question

You can escape parenthesis in grep by standard adding \. But i want to escape parenthesis in egrep which uses \( as a grouping mechanism like sed. I want to write egrep expression to parse the following:

log_message(_sanitize("my string"));

You got it wrong: `grep` uses `\(...\)` for grouping, and `egrep` uses `(...)`. Thus: `egrep 'log_message\(_sanitize\("my string"\)\)'` — lcd047, Jul 17 '15 at 18:51
This was helpful for me for regex with sed with capture groups: https://stackoverflow.com/a/30431410/470749 — Ryan, Sep 29 '22 at 20:46

that other guy · Accepted Answer · 2015-07-17T20:02:07.493

3

Parentheses in grep (BRE) require no escaping, they match themselves literally:

$ grep -o '(a)' <<< '(a)'
(a)

In egrep (ERE) parentheses are used for grouping. They can be escaped to match literal parentheses:

$ egrep -o '(a)' <<< '(a)'
a

$ egrep -o '\(a\)' <<< '(a)'
(a)

You can therefore just add escaping to yours to match the expression literally:

$ egrep -o 'log_message\(_sanitize\("my string"\)\);' \
    <<< 'log_message(_sanitize("my string"));'
log_message(_sanitize("my string"));

edited Jul 17 '15 at 20:02

answered Jul 17 '15 at 18:51

that other guy

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You have a typo error. The output of `grep -o '(a)' <<< '(a)'` should be `(a)`. – alvits Jul 17 '15 at 19:54
1

Copy-paste fail. Thanks! – that other guy Jul 17 '15 at 20:02

score 2 · Answer 2 · answered Jul 17 '15 at 18:50

2

One way is to put the ( in a character class like:

 egrep 'log_message[(]_sanitize[(]"my string"[)][)];' <file>

answered Jul 17 '15 at 18:50

Eric Renouf

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How to escape parenthesis in egrep

2 Answers2