awk Row Manipulation Modifying rows on-the-fly (e.g. to fix Windows line-endings)
Example
If a file may contain Windows or Unix-like line endings (or even a mixture of both) then the intended text replacement may not work as expected.
Sample:
$ echo -e 'Entry 1\nEntry 2.1\tEntry 2.2\r\nEntry 3\r\n\r\n' \
> | awk -F'\t' '$1 != "" { print $1 }' \
> | hexdump -c
0000000 E n t r y 1 \n E n t r y 2 .
0000010 1 \n E n t r y 3 \r \n \r \n
000001d
This can be easily fixed by an additional rule which is inserted at the beginning of the awk script:
/\r$/ { $0 = substr($0, 1, length($0) - 1) }
Because the action does not end with next, the following rules are applied as before.
Sample (with fix of line-endings):
$ echo -e 'Entry 1\nEntry 2.1\tEntry 2.2\r\nEntry 3\r\n\r\n' \
> | awk -F'\t' '/\r$/ { $0 = substr($0, 1, length($0) - 1) } $1 != "" { print $1 }' \
> | hexdump -c
0000000 E n t r y 1 \n E n t r y 2 .
0000010 1 \n E n t r y 3 \n
000001a
