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bashshellunixgnu-coreutils

Using join for cartesian product

In the comments of an answer started a discussion related to using GNU coreutils' join for creating cartesian product of two files. A fellow user suggested that:

$ join -j 2 -t '' file1 file2

produces cartesian product of file1 and file2:

$ cat file1
1
2
$ cat file2
a
b

Expected output: 

$ join -j 2 -t '' file1 file2
1a
1b
2a
2b

Well, I'm getting:

$ join -t '' -j 2 file1 file2

1
a

1
b

2
a

2
b

I've tested in 2 Debian Jessies (join (GNU coreutils) 8.23) and a Ubuntu Trusty Tahr (join (GNU coreutils) 8.21) with C and en_US.utf8 locales (all systems installed and administered by different parties). Reportedly join behaves as expected in OS X and a system with join (GNU coreutils) 8.22.

Has anyone ran into this before? What am I doing wrong?

Solution

  • you need use as delimiter '\0' 

    join -t '\0' -j 2 file1 file2