"grep <pattern> <files>" is not the same as "cat <files> | grep <pattern>", in t... | Hacker News

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omoikane on Jan 18, 2015 | parent | context | favorite | on: Command-line tools can be faster than your Hadoop ...

"grep <pattern> <files>" is not the same as "cat <files> | grep <pattern>", in that the former will prefix lines with filenames if there is more than one input file. What you want instead is "grep -h <pattern> <files>".

The advantage of using cat, therefore, is the few seconds of laziness saved in not reading the manual.

salgernon on Jan 18, 2015 [–]

The advantage to using "cat foo | grep pattern" is that it is trivial to ^p and edit the pattern before adding the next pipeline sequence.

philsnow on Jan 19, 2015 | [–]

fwiw

    $ <filename grep <pattern>

no shell I'm aware of restricts you to placing redirections at the end, you can throw them on the beginning no problem.

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