How to add line numbers in unix shell output

How to add line numbers in unix shell output

To display line numbers easily on a shell output, pipe it to "nl" command - line number filter.

Quote:

NL(1) FreeBSD General Commands Manual NL(1)

NAME
nl -- line numbering filter

SYNOPSIS
nl [-p] [-b type] [-d delim] [-f type] [-h type] [-i incr] [-l num]
[-n format] [-s sep] [-v startnum] [-w width] [file]

DESCRIPTION
The nl utility reads lines from the named file or the standard input if
the file argument is omitted, applies a configurable line numbering fil-
ter operation and writes the result to the standard output.

The nl utility treats the text it reads in terms of logical pages.
Unless specified otherwise, line numbering is reset at the start of each
logical page. A logical page consists of a header, a body and a footer
section; empty sections are valid. Different line numbering options are
independently available for header, body and footer sections.

The starts of logical page sections are signalled by input lines contain-
ing nothing but one of the following sequences of delimiter characters:

Line Start of
\:\:\: header
\:\: body
\: footer

If the input does not contain any logical page section signalling direc-
tives, the text being read is assumed to consist of a single logical page
body.

This can be done with awk also, but I find this easier:

Code:

# ls
file1   file10  file2   file3   file4   file5   file6   file7   file8   file9
# ls | nl
     1  file1
     2  file10
     3  file2
     4  file3
     5  file4
     6  file5
     7  file6
     8  file7
     9  file8
    10  file9