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grep can't be fed "raw" strings when used from the command-line, since some characters need to be escaped to not be treated as literals. For example:
$ grep '(hello|bye)' # WON'T MATCH 'hello' $ grep '\(hello\|bye\)' # GOOD, BUT QUICKLY BECOMES UNREADABLE I was using printf to auto-escape strings:
$ printf '%q' '(some|group)\n' \(some\|group\)\\n This produces a bash-escaped version of the string, and using backticks, this can easily be passed to a grep call:
$ grep `printf '%q' '(a|b|c)'` However, it's clearly not meant for this: some characters in the output are not escaped, and some are unnecessarily so. For example:
$ printf '%q' '(^#)' \(\^#\) The ^ character should not be escaped when passed to grep.
Is there a cli tool that takes a raw string and returns a bash-escaped version of the string that can be directly used as pattern with grep? How can I achieve this in pure bash, if not?
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grep is one of the most useful and powerful commands in Linux for text processing. grep searches one or more input files for lines that match a regular expression and writes each matching line to standard output.
Raw strings help you get the "source code" of a RegEx safely to the RegEx parser, which will then assign meaning to character sequences like \d , \w , \n , etc...
Python raw string is created by prefixing a string literal with 'r' or 'R'. Python raw string treats backslash (\) as a literal character. This is useful when we want to have a string that contains backslash and don't want it to be treated as an escape character.
According to Python docs, raw string notation (r"text") keeps regular expressions meaningful and confusion-free. Without it, every backslash ('\') in a regular expression would have to be prefixed with another one to escape it. For example, the two following lines of code are functionally identical − >>> re.
If you want to search for an exact string,
grep -F '(some|group)\n' ... -F tells grep to treat the pattern as is, with no interpretation as a regex.
(This is often available as fgrep as well.)
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