report if any one record is not of matching size using sed

Question

how can I use sed to report any first record that is not of size 21 in a file?

I don't want sed to scan the complete file and get out as soon as the first record which is not of size 21 is found.

i have the sed command i am not sure how to break out of it . — Ahmad S, May 16 '18 at 19:00
Possible duplicate of sed command to find lines which are not of specific size — DopeGhoti, May 16 '18 at 19:31
In fairness, this is a duplicate of what the other question was apparently meant to be as opposed to what the other question is stated to be. — DopeGhoti, May 16 '18 at 19:50

Kusalananda · Answer 1 · 2018-05-16T19:12:34.717

1

Using awk (this would be easiest):

awk 'length != 21 { printf("Line of length %d found\n", length); exit }' file

Or, as part of a shell script,

if ! awk 'length != 21 { exit 1 }' file; then
    echo 'Line of length != 21 found (or awk failed to execute properly)'
else
    echo 'All lines are 21 characters (or the file is empty)'
fi

Using sed:

sed -nE '/^.{21}$/!{p;q;}' file

With GNU sed, you would be able to do

if ! sed -nE '/.{21}$/!q 1' file; then
   echo 'Line with != 21 characters found (or sed failed to run properly)'
else
   echo 'All lines are 21 characters (or file is empty)'
fi

edited May 16 '18 at 19:12

answered May 16 '18 at 18:42

Kusalananda

333,661

using sed please – Ahmad S May 16 '18 at 19:00
@AhmadS See updated answer. – Kusalananda May 16 '18 at 19:12

score 1 · Accepted Answer · answered May 16 '18 at 19:08

1

Based on this answer to your previous question

sed -n '/^.\{21\}$/! {p;q;}' file

answered May 16 '18 at 19:08

steeldriver

81,074

score 1 · Answer 3 · answered May 16 '18 at 21:36

1

With GNU grep:

if line=$(grep -Exnvm1 '.{21}' < file); then
  printf >&2 'Found "%s" which is not 21 characters long\n' "$line"
fi

(-n above includes the line number)

answered May 16 '18 at 21:36

Stéphane Chazelas

544,893

report if any one record is not of matching size using sed

3 Answers3