BASH: Display two files side by side simultaneously

Question

I'm working on a bash script, and I want to print two files side by side. One file is filled with IPv4 addresses and the other one is filled with IPv6 addresses. I tried,

pr -mtw $WIDTH $FILE1 $FILE2

but it cut the output.

┌────┤IPV4├─────┬─────────────────┤IPV6├────────────────┐
 224.0.0.1       2001:0db8:0000:
 192.0.2.128     ff02::1
 192.0.2.128     2001:0db8:0000:
 192.0.2.128     ::
                 2001:0db8:0000:
                 2001:db8:0:0:0:
                 2001:db8::ff00:
                 0000:0000:0000:
                 ::1
                 fe80::
                 ::ffff:192.0.2.
                 ::192.0.2.128

I also tried,

paste $FILE1 $FILE2  | awk '$1=$1' OFS='\t '

and the output was,

┌────┤IPV4├─────┬─────────────────┤IPV6├────────────────┐
224.0.0.1    2001:0db8:0000:0042:0000:8a2e:0370:7334
192.0.2.128  ff02::1
192.0.2.128  2001:0db8:0000:0000:0000:ff00:0042:8329
192.0.2.128  ::
2001:0db8:0000:0000:0000:ff00:0042:8329
2001:db8:0:0:0:ff00:42:8329
2001:db8::ff00:42:8329
0000:0000:0000:0000:0000:0000:0000:0001
::1
fe80::
::ffff:192.0.2.128
::192.0.2.128

I want the output to be something like,

┌────┤IPV4├─────┬─────────────────┤IPV6├────────────────┐
 224.0.0.1       2001:0db8:0000:0042:0000:8a2e:0370:7334
 192.0.2.128     ff02::1
 192.0.2.128     2001:0db8:0000:0000:0000:ff00:0042:8329
 192.0.2.128     ::
                 2001:0db8:0000:0000:0000:ff00:0042:8329
                 2001:db8:0:0:0:ff00:42:8329
                 2001:db8::ff00:42:8329
                 0000:0000:0000:0000:0000:0000:0000:0001
                 ::1
                 fe80::
                 ::ffff:192.0.2.128
                 ::192.0.2.128

FILE1:

 224.0.0.1
 192.0.2.128
 192.0.2.128
 192.0.2.128

FILE2:

 2001:0db8:0000:0042:0000:8a2e:0370:7334
 ff02::1
 2001:0db8:0000:0000:0000:ff00:0042:8329
 ::
 2001:0db8:0000:0000:0000:ff00:0042:8329
 2001:db8:0:0:0:ff00:42:8329
 2001:db8::ff00:42:8329
 0000:0000:0000:0000:0000:0000:0000:0001
 ::1
 fe80::
 ::ffff:192.0.2.128
 ::192.0.2.128

Note that there is a space at the beginning of each line. Any ideas?

Answer 1

Using awk, tr and GNU paste command:-

$ paste file1 file2 | awk -v FS='\t' '{printf("%-15s %s\n",$1,$2)}' | \
            awk '{sub(/^/, " ", $0)}1'

 224.0.0.1       2001:0db8:0000:0042:0000:8a2e:0370:7334
 192.0.2.128     ff02::1
 192.0.2.128     2001:0db8:0000:0000:0000:ff00:0042:8329
 192.0.2.128     ::
                 2001:0db8:0000:0000:0000:ff00:0042:8329
                 2001:db8:0:0:0:ff00:42:8329
                 2001:db8::ff00:42:8329
                 0000:0000:0000:0000:0000:0000:0000:0001
                 ::1
                 fe80::
                 ::ffff:192.0.2.128
                 ::192.0.2.128

You can optimize the last piped awk with 2nd one, was not sure exactly how to do it. Otherwise, this works!

Answer 2

You can use the command column:

paste -d, file1 file2 | column  -s',' -n -t

The paste command will join both file line by line with the separator ,.

The column command will replace the , by the necessary spaces to have it indented correctly (with option -t). The -n is saying to column to fill empty column. Note the option -nis Debian specific.

Answer 3

This works fine

paste "$FILE1" "$FILE2" | awk -F'\t' '{printf("%-16s%s\n", $1, $2)}'