Using sed and regex to replace a group in a string

Question

I have a string in a file:

0x0c42a103001815f6, MF0;r-hpc-sw07:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600401

0x0c42a10300181636, MF0;r-hpc-sw09:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600447

0x98039b03008d5d44, MF0;r-hpc-sw08:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600476

0x98039b0300a8b786, MF0;r-hpc-sw10:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600529

======================================

0x0c42a103001815ee, 1, 0x0c42a1030018162e, 1, 0

0x0c42a1030018162e, 8, 0x98039b03008d5d3c, 8, 0

0x0c42a103001815ee, 8, 0x98039b0300a8b77e, 8, 0

0x98039b03008d5d3c, 1, 0x98039b0300a8b77e, 1, 0

I would like to replace in the second paragraph only the last number '0' to '9':

0x0c42a103001815f6, MF0;r-hpc-sw07:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600401

0x0c42a10300181636, MF0;r-hpc-sw09:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600447

0x98039b03008d5d44, MF0;r-hpc-sw08:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600476

0x98039b0300a8b786, MF0;r-hpc-sw10:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600529

======================================

0x0c42a103001815ee, 1, 0x0c42a1030018162e, 1, 9

0x0c42a1030018162e, 8, 0x98039b03008d5d3c, 8, 9

0x0c42a103001815ee, 8, 0x98039b0300a8b77e, 8, 9

0x98039b03008d5d3c, 1, 0x98039b0300a8b77e, 1, 9

I tried using: sed -i -r 's|(^([[:alnum:]]+)([[:punct:]]+)([[:space:]]+)([[:digit:]]+)([[:punct:]]+)([[:space:]]+)([[:alnum:]]+)([[:punct:]]+)([[:space:]]+)([[:digit:]]+)([[:punct:]]+)([[:space:]]+)(0)$)|\19|g'

But got:

0x0c42a103001815f6, MF0;r-hpc-sw07:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600401

0x0c42a10300181636, MF0;r-hpc-sw09:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600447

0x98039b03008d5d44, MF0;r-hpc-sw08:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600476

0x98039b0300a8b786, MF0;r-hpc-sw10:MQM8700/U1 , Valid , 2022 Mar 29 11:35:54:600529

======================================

0x0c42a103001815ee, 1, 0x0c42a1030018162e, 1, 09

0x0c42a1030018162e, 8, 0x98039b03008d5d3c, 8, 09

0x0c42a103001815ee, 8, 0x98039b0300a8b77e, 8, 09

0x98039b03008d5d3c, 1, 0x98039b0300a8b77e, 1, 09

Any suggestions?

Please read stackoverflow.com/help/formatting and then edit your question to show all input, output, and code as Code Blocks. — Ed Morton
– Ed Morton, Commented Mar 29, 2022 at 12:36

Wiktor Stribiżew · Accepted Answer · 2022-03-29 09:41:07Z

You get the 09 as a result because you capture the whole line and append 9 to it when replacing with \19.

You may move the capturing group #1 end boundary to the location before 0:

sed -i -r 's|^([[:alnum:]]+[[:punct:]]+[[:space:]]+[[:digit:]]+[[:punct:]]+[[:space:]]+[[:alnum:]]+[[:punct:]]+[[:space:]]+[[:digit:]]+[[:punct:]]+[[:space:]]+)(0)$|\19|g' file

Or, since the punctuation in your string is actually just a comma you can simplify this to

sed -i -r 's|^([[:alnum:]]+,[[:space:]]+[0-9]+,[[:space:]]+[[:alnum:]]+,[[:space:]]+[0-9]+,[[:space:]]+)0$|\19|g' file

Note you only need to capture what you need to keep, and you can wrap pattern sequences with a single capturing group. If you do not need the separate values between commas, etc., you need not capture their individual patterns.

See the online demo:

#!/bin/bash
s='0x0c42a103001815f6, MF0;r-hpc-sw07:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600401
0x0c42a10300181636, MF0;r-hpc-sw09:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600447
0x98039b03008d5d44, MF0;r-hpc-sw08:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600476
0x98039b0300a8b786, MF0;r-hpc-sw10:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600529
======================================
0x0c42a103001815ee, 1, 0x0c42a1030018162e, 1, 0
0x0c42a1030018162e, 8, 0x98039b03008d5d3c, 8, 0
0x0c42a103001815ee, 8, 0x98039b0300a8b77e, 8, 0
0x98039b03008d5d3c, 1, 0x98039b0300a8b77e, 1, 0'
sed -E 's|^([[:alnum:]]+,[[:space:]]+[0-9]+,[[:space:]]+[[:alnum:]]+,[[:space:]]+[0-9]+,[[:space:]]+)0$|\19|g' <<< "$s"

Output:

0x0c42a103001815f6, MF0;r-hpc-sw07:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600401
0x0c42a10300181636, MF0;r-hpc-sw09:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600447
0x98039b03008d5d44, MF0;r-hpc-sw08:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600476
0x98039b0300a8b786, MF0;r-hpc-sw10:MQM8700/U1 , Valid    , 2022 Mar 29 11:35:54:600529
======================================
0x0c42a103001815ee, 1, 0x0c42a1030018162e, 1, 9
0x0c42a1030018162e, 8, 0x98039b03008d5d3c, 8, 9
0x0c42a103001815ee, 8, 0x98039b0300a8b77e, 8, 9
0x98039b03008d5d3c, 1, 0x98039b0300a8b77e, 1, 9

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