nl - line numbering filter
nl [-htype] [-btype]
[-ftype] [-vstart#] [-iincr]
[-p] [-lnum] [-wwidth]
[-nformat] [-ddelim] [file]
The nl command prints a file, or, when no
file argument is given, standard input, preceding lines with line
numbers on the left.
Lines with special content are taken as page delimiters. Three
parts of pages are distinguished: header, body and footer. Each part is
started when a line consisting only of the following characters appears in
input:
| Line contents |
Start of |
| \:\:\: |
header |
| \:\: |
body |
| \: |
footer |
Line numbers are reset each time a header begins. The start of the file is
considered a body part until a line marking another part appears.
The following options alter the behavior of nl:
- -btype
- Specifies which lines in a body part are numbered, where type is
one of the following:
- a
- Number all lines, unless otherwise specified by the -l option.
- t
- Number all non-empty lines.
- n
- Number no lines.
- pstring
- Number all lines that match the regular expression string. Regular
expressions are as in ed(1); /usr/5bin/nl uses simple
regular expressions, /usr/5bin/posix/nl,
/usr/5bin/posix2001/nl, and /usr/5bin/s42/nl use basic
regular expressions.
- The default is t.
- -ddelim
- Change the special characters that delimit parts of a page to the two
characters in delim. If delim consists of only one
character, the second character remains the default, `:'.
- -ftype
- Specifies which lines in a footer part are numbered, where type has
the format described for -b. The default is n.
- -htype
- Specifies which lines in a header part are numbered, where type has
the format described for -b. The default is n.
- -iincr
- Line numbers are increased by incr, which defaults to 1.
- -lnum
- For the -ba, -fa, and -ha options, specifies which
line of adjacent blank lines is printed. The default is 1 (print all blank
lines).
- -nformat
- Sets the format of line numbers, where format is one of:
- ln
- left-justified, preceded by blanks
- rn
- right-justified, preceded by blanks
- rz
- right-justified, preceded by zeros
- The default is rn.
- -p
- Line numbers are not reset at the start of each header when this option is
present.
- -ssep
- Sets the string that separates line number and line content in output,
default is a tabulator.
- -vstart#
- Each page is numbered starting at start#, which defaults to 1.
- -wwidth
- Sets the width of line numbers. If a number has fewer digits than
width, it is padded as described for the -n option; if it
has more digits, only the last width digits are printed. The
default width is 6.
The file argument can appear between options. For
/usr/5bin/nl and /usr/5bin/s42/nl, option and option argument
must not be separated; if an option is not immediately followed by its
argument, the default value is used. /usr/5bin/posix/nl and
/usr/5bin/posix2001/nl require an option argument and accept it
regardless of space between option and argument.
- LANG,
LC_ALL
- See locale(7).
- LC_COLLATE
- Affects the collation order for range expressions, equivalence classes,
and collation symbols in basic regular expressions.
- LC_CTYPE
- Determines the mapping of bytes to characters.
To number all lines in a file, effectively disabling header and
footer recognition since no line can contain a second newline character and
thus the condition is never met:
Note that there is no white space other than the newline character between
´ ´.
To number all lines that are not empty and contain at least one
non-blank character:
The characters between [ ] are: a circumflex, a space, and a tabulator.
Since the default width causes line numbers to be truncated if
they consist of more than six digits, the -w option should be used to
increase this value if higher numbers are to be expected.