.TH NL 1 sbase\-VERSION
.SH NAME
nl \- number lines
.SH SYNOPSIS
.B nl
.RB [ \-b
.IR mode ]
.RB [ \-i
.IR increment ]
.RB [ \-s
.IR separator ]
.RI [ file ...]
.SH DESCRIPTION
.B nl
reads each file in sequence and writes it to stdout with non\-empty lines
numbered.  If no file is given, nl reads from stdin.
.SH OPTIONS
.TP
.BI \-b " mode"
defines which lines will be numbered:
.PD 0
.RS
.TP
.B a
all lines.
.TP
.B n
no lines.
.TP
.BI p pattern
only lines which match
.IR pattern ,
a regular expression as defined in
.IR regex (7).
.TP
.B t
only non\-empty lines (default).
.RE
.PD
.TP
.BI \-i " increment"
defines the increment between numbered lines.
.TP
.BI \-s " separator"
defines the string used to separate line numbers and lines.  By default this is
a tab.