Printing 2 files side by side

[sc0ttman]

paste command

How to print files side by side.

Adapted from https://www.baeldung.com/linux/merge-files-line-by-line,
which has a nice AWK solution too.

Here is file1:

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# cat /tmp/a
1111
2222
3333
4444

666666

and file2:

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# cat /tmp/b
aaaa
bbbb
cccc
dddd
eeeeeeee
ffff

Notice they don't have matching lengths, and have some empty lines.

Let's use paste to create a nicely arranged, TAB-delmited set of columns like:

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file1_line1   file2_line1
file1_line2   file2_line2
file1_line3   file2_line3
file1_line4   file2_line4

We'll use column to help us arrange the the output correctly.

The -t option tells column to align things nicely in a table format.

The -n option tells column not to merge multiple empty separators (\t),
which will keep eveything nicely in its columns, accounting for the empty lines.

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# paste /tmp/a /tmp/b | column -t -n
1111    aaaa
2222    bbbb
3333    cccc
4444    dddd
        eeeeeeee
666666  ffff

Note, you can change the delimeter that paste uses with -d (and column too, with -s):

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# paste -d'|' /tmp/a /tmp/b | column -t -n -s'|'
1111    aaaa
2222    bbbb
3333    cccc
4444    dddd
        eeeeeeee
666666  ffff

To arrange your data a totally different way, you can make paste put
everything from file1 along the first line of your output file, and
everything from file2 on the second line:

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file1_line1   file1_line2   file1_line3 ...
file2_line1   file2_line2   file2_line3 ...

You achieve this with the -s|--serial option:

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# paste -d '|' -s /tmp/a /tmp/b
1111|2222|3333|4444||666666
aaaa|bbbb|cccc|dddd|eeeeeeee|ffff