How can I add numbers to the beginning of every line in a file?
E.g.:
This is the text from the file.
Becomes:
000000001 This is 000000002 the text 000000003 from the file.
AWK's printf, NR
and $0
make it easy to have precise and flexible control over the formatting:
~ $ awk '{printf("%010d %s\n", NR, $0)}' example.txt
0000000001 This is
0000000002 the text
0000000003 from the file.