nl reads lines from the named file, or the
standard input if no file is named, and reproduces the
lines on the standard output. Lines are numbered on the left in
accordance with the command options in effect.
nl views the text it reads in terms of logical pages. 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 (for example, no numbering of
header and footer lines while numbering blank lines only in the
body).
The start of logical page sections is signaled by input lines
containing nothing but one or more pairs of
backslash-followed-by-colon:
Page section
Line contents
Header
\:\:\:
Body
\:\:
Footer
\:
Unless signaled otherwise, nl assumes the text being read
is in a single logical page body.
Command options may appear in any order and may be intermingled with
an optional filename.
Only one file may be named. The options are:
-btype
Specifies which logical page body lines are to be
numbered. Recognized types and their meaning are:
a, number all lines; t,
number only lines consisting entirely of printable characters;
n, no line numbering; pstring, number
only lines that contain the regular expression specified in
string. Default type for logical page body is
t.
-ddelim
Specifies the two characters that show the start of a logical page
section. The default characters are \:; if only one
character is given for delim, nl assumes that
the second should be ``:''.
-ftype
Same as -btype except for footer. Default for
logical page footer is n (no lines numbered).
-htype
Same as -btype except for header. Default
type for logical page header is n (no lines
numbered).
-iincr
incr is the increment value used to number logical page
lines. The default is 1.
-lnum
num is the number of blank lines to be considered as
one. For example, -l2 results in only the second adjacent
blank being numbered (if the appropriate -ha,
-ba, and/or -fa option is set). The default is
1.
-nformat
format is the line numbering format. Recognized
formats are:
ln
left justified, leading zeroes suppressed
rn
right justified, leading zeroes suppressed
rz
right justified, leading zeroes kept
Default format is rn (right justified).
-p
Does not restart numbering at logical page delimiters.
-ssep
sep is the character(s) used in separating the line number
and the corresponding text line. Default sep is a tab.
-vstart#
start# is the initial value used to number logical page
lines. The default is 1.
-wwidth
width is the number of characters to be used for the line
number. The default width is 6.
Examples
Number the lines of the C program source file foo.c and
print it:
2:1992, Information technology