#3166 PR open: WIP: Use the new TextPrefix function¶

Labels: enhancement

jsmeix opened issue at 2024-02-27 11:51:¶

Use the new TextPrefix function

• Type: Enhancement

• Impact: None
  No impact for users.
  But for us:
  More standardized code by a general TextPrefix function
  instead of individual sed calls.
  Easier to find the code places where text is prefixed.
  Easier to properly indent multi-line texts in the code.

• Reference to related issue (URL):
  https://github.com/rear/rear/pull/3160

• How was this pull request tested?
  https://github.com/rear/rear/pull/3160#issuecomment-1954251341
  and
  https://github.com/rear/rear/pull/3160#issuecomment-1954258836

jsmeix commented at 2024-02-27 13:50:¶

As always it is more complicated than one thinks,
cf. RFC 1925 item 8.

Something like

COMMAND | TextPrefix '# '

cannot be used in general.
It can only be used when the output of COMMAND
is not indented or when that indentation is meaningless
because TextPrefix removes (meaningful) indentation.

For example the above
https://github.com/rear/rear/pull/3166/commits/9688568ec2d9f7f6031216424c498f1d800822ef
should be OK because plain 'lsdasd' output is not indented
see the example in
http://ubuntu-on-big-iron.blogspot.com/2018/03/ubuntu-ccw-howto-2-of-4-DASD.html

... lsdasd

Bus-ID     Status      Name      Device  Type  BlkSz  Size      Blocks
=======================================================================
0.0.2608   active      dasda     94:0    ECKD  4096   7043MB    1803060
0.0.2619   active      dasdb     94:4    ECKD  4096   21129MB   5409180
...

In contrast e.g. lsdasd -l ... output is indented
as shown in
https://www.ibm.com/docs/en/linux-on-z?topic=c-lsdasd-2

lsdasd -l 0.0.4d82
0.0.4d82/dasdd/94:12
  status:                             active
  type:                               ECKD
  blksz:                              4096
  ...

Another example where COMMAND output indentation
is meaningful and needed is the
"Example 'mdadm --misc --detail $raiddevice' output"
in layout/save/GNU/Linux/210_raid_layout.sh

/dev/md/raid1sdab:
           Version : 1.0
     Creation Time : Wed Oct 13 13:17:13 2021
        Raid Level : raid1
        Array Size : 12582784 (12.00 GiB 12.88 GB)
                  ...

where TextPrefix '# ' would result

# /dev/md/raid1sdab:
# Version : 1.0
# Creation Time : Wed Oct 13 13:17:13 2021
# Raid Level : raid1
# Array Size : 12582784 (12.00 GiB 12.88 GB)
# ...

Not a big fault but less readable as the indented output.

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[Export of Github issue for rear/rear.]