Xargs Command Lines – How to Show Without Running

xargs

A fair number of linux commands have a dry-run option that will show you what they're going to do without doing it. I see nothing in the xargs man page that does that and no obvious way to emulate it.

(my specific use case is troubleshooting long pipelines, though I'm sure there are others)

Am I missing something?

Best Answer

Put an echo in front of the command to run?

$ echo a b c d e | xargs -n2 echo rm
rm a b
rm c d
rm e

Related Solutions

What does xargs do if it’s used without any parameter

quoting the manpage:

xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is /bin/echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored.

Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you.

Xargs: running command once with all arguments

... | xargs -0 rspec -f documentation

Note that this can call rspec multiple times if the command line would be too long. This isn't an issue with rspec since the reason to call it once is performance, but don't use it for something like xargs -0 tar cf archive.tar where any second, third, … run would create an archive overwriting the output of the previous runs.

Best Answer

Related Solutions

What does xargs do if it’s used without any parameter

Xargs: running command once with all arguments

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