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I have seen solutions of splitting a file with respect to pattern matching and line matching but what I want is the following. The scenario is, let's say I have a file file1 -


Now I want to split this file into 3 different files just based on the first column where the 1st file would be all the lines containing A.B in the first column, the 2nd file should have all the lines with A.X and so on.

If the first column changes in any way, there should be a new file created for those lines. Is there any way of doing it with bash or awk?

Since there is no way of actually knowing before hand what the first column value is, I wasn't able to use any feature like split or cut. Thanks for the help in advance!

marked as duplicate by don_crissti, Community Jul 22 '16 at 22:23

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awk -F\| '{print>$1}' file1

This writes each line to a file named after the first column.

How it works:

  • -F\| sets the field separator to |.

  • print>$1 prints the current line to a file whose name is the first field.

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    That's what I wanted. Thank you, will accept in 2 minutes. – Zzrot Jul 22 '16 at 22:23
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    (what surprises me about this, is that a second occurrence of the first field doesn't open a new instance of the file and write over the previous one. that is, that ">>" isn't necessary. ...been using shell for too long, i guess) – Theophrastus Jul 22 '16 at 22:24
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    @Theophrastus That would be shell behavior. Awk is different. With awk, > will overwrite a previously existing file but, and this is where it differs from shell, while the awk command is running, > appends. – John1024 Jul 22 '16 at 22:26
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    @user3768495 awk -F\| '{print>"subfolder/"$1}' file1 – John1024 Nov 14 '17 at 19:04
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    Tried a bunch of different ways to concatenate the subfolder with $1 but without success. Thanks for providing the answer, @John1024! – user3768495 Nov 14 '17 at 22:16

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