Sunday, 26 May 2013

Why is xargs necessary?

Why is xargs necessary?

Suppose I want to remove all files in a directory except for one named "notes.txt". I would do this with the pipeline, ls | grep -v "notes.txt" | xargs rm. Why do I need xargs if the output of the second pipe is the input that rm should use?
For the sake of comparison, the pipeline, echo "#include <knowledge.h>" | cat > foo.c inserts the echoed text into the file without the use of xargs. What is the difference between these two pipelines?

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