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I am reading a list of outputs for pipewire in a shell script and looking for a specific entry. I don't know the exact name but I know the words that are in it. To find it I am using multiple greps for each word I know will be in the entry

pw-cli list-objects | grep node.name | grep output | grep pci | grep analog

Is there an alternative to doing this? Thank you.

muru
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Justin Kachele
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    Please [edit] your question to show what the sample input would be and your expected output. As written your code looks for lines that contain all of those strings in the same line. – Jim L. Jun 06 '23 at 21:44

2 Answers2

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I'd use awk for this:

pw-cli list-objects | awk '/node\.name/ && /output/ && /pci/ && /analog/'

Or maybe perl if I needed perl's regex syntax, or other perl language features or library modules (neither of which are actually needed for this example):

pw-cli list-objects | 
  perl -n -e 'print if (/node\.name/ && /output/ && /pci/ && /analog/)'

There are two main benefits in using awk or perl for this:

  1. it will match input lines regardless of the order of words in the input. i.e. a regex like node\.name.*output.*pci.*analog will match only if those words are in the input line in exactly that order. The awk or perl one-liners above will match if ALL four words are present anywhere in the input line, in any order - this is equivalent to the way you've chained multiple greps together in the pipeline.

    You could use extended regexps with alternations (|) for every placement variation, but with four words, you'd need 16 alternate versions to match every possible arrangement, so that's kind of impractical - (a.*b.*c.*d)|(a.*c.*b.*d)|(a.*b.*d.*c)|.........

  2. You can use any combination of && (AND), || (OR), ! (negation), and parentheses to construct an arbitrarily complex boolean conditional. You can also combine with any other awk or perl syntax that returns a true or false result (e.g. calculations & comparisons based on fields within the input line).

cas
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Yes, by using "regular expressions". Read man grep.

# if they're on the same linr
pw-cli | grep 'node\.name.*output.*pci.*analog'
# or if they're not
pw-cli | grep 'node\.name|output<pci|analog'
waltinator
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