Set operations in the unix shell are possible:


And the solutions from this site are very user-friendly. With "user" being a sub set of all people loving unix :-)

I search a library to do things like this:

set-ops fileA - fileB

With "fileX" being a set of lines in a file.

I want a easy to use tool:

  • The tool can use some kind of sorting for the implementation, but me (the user) don't want to call it.
  • I don't want to call "comm -3" or other things which are hard to remember.

This results into the restriction that the set members are strings which must not contain the newline character. But that's ok.

Needed features:

  • open source
  • easy to install (for me this means: rpm/dpkg/pip package)
  • available on linux.
  • Above link has a list of supported set operations (Set Membership to Maximum). Most of them should be implemented.
  • You want to do everything within the shell?
    – Bill Bell
    Nov 14, 2016 at 19:23
  • @BillBell what is "shell"? If I call a command like grep or sed, then there is not big difference to calling a special command, or a python/perl script. Short answer: I want to call the set operations tool via shell. I don't care at all about the implementation (it can be python, perl, c, go, ....). Dear Bill, did this answer your question?
    – guettli
    Nov 15, 2016 at 8:52

3 Answers 3


I wonder why you did not mention his other post: http://www.catonmat.net/blog/set-operations-in-unix-shell-simplified/ that actually has the list of most set operations - the the scripts are available for download as .txt.

  • Have you looked at the text file? It does not provide commands for the shell. I think it is just an other format (text instead of html).
    – guettli
    Nov 15, 2016 at 15:09
  • Yeah, I know. The question is - is this the sort of thing you are looking for or you want a custom script library, where say: set_union file1 file2 ... filen executes cat set1 set2 ... setn and say set_min set fires away head -1 <(sort set)? Nov 15, 2016 at 15:37

I wrote a python script to make set operations available on the command line.

Source Code is here: https://github.com/guettli/reprec/blob/master/setops/init.py

Since I wanted it to be ready before this bounty finishes, the source is in the repo of my reprec tool.

You can install it via pip: https://pypi.python.org/pypi/reprec


===> setops -h
usage: setops [-h] set1 operator set2

  union Aliases: | + or
  intersection Aliases: & and
  difference Aliases: - minus
  symmetric_difference Aliases: ^

positional arguments:

optional arguments:
  -h, --help  show this help message and exit

I might as well say what I was thinking when I commented! :)

Have you considered using Sage? It has a fairly complete collection of set operations, and also allows Python code within itself. If the text files you contemplate manipulating are not too large then you could write a quite small routine to convert a text file to a Sage set then use the Sage operators to manipulate instances of these sets.

  • If I have two files like in the question text (fileA, fileB). The content is newline separated filenames. How can I do set operations on the shell with Sage?
    – guettli
    Nov 15, 2016 at 15:35
  • You can write Sage scripts that are callable from the shell. See doc.sagemath.org/html/en/tutorial/….
    – Bill Bell
    Nov 15, 2016 at 15:43
  • Hmm Sage is GPL. I am afraid that I need to open source my scripts which use Sage, since the GPL is a viral licence.
    – guettli
    Nov 15, 2016 at 16:11

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