xref: /freebsd/usr.bin/fmt/fmt.1 (revision f81cdf24ba5436367377f7c8e8f51f6df2a75ca7)
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28.\" Modified by Gareth McCaughan to describe the new version of `fmt'
29.\" rather than the old one.
30.Dd October 29, 2020
31.Dt FMT 1
32.Os
33.Sh NAME
34.Nm fmt
35.Nd simple text formatter
36.Sh SYNOPSIS
37.Nm
38.Op Fl cmnps
39.Op Fl d Ar chars
40.Op Fl l Ar num
41.Op Fl t Ar num
42.Op Ar goal Oo Ar maximum Oc | Fl Ns Ar width | Fl w Ar width
43.Op Ar
44.Sh DESCRIPTION
45The
46.Nm
47utility is a simple text formatter which reads the concatenation of input
48files (or standard input if none are given) and produces on standard
49output a version of its input with lines as close to the
50.Ar goal
51length
52as possible without exceeding the
53.Ar maximum .
54The
55.Ar goal
56length defaults
57to 65 and the
58.Ar maximum
59to 10 more than the
60.Ar goal
61length.
62Alternatively, a single
63.Ar width
64parameter can be specified either by prepending a hyphen to it or by using
65.Fl w .
66For example,
67.Dq Li fmt -w 72 ,
68.Dq Li fmt -72 ,
69and
70.Dq Li fmt 72 72
71all produce identical output.
72The spacing at the beginning of the input lines is preserved in the output,
73as are blank lines and interword spacing.
74Lines are joined or split only at white space; that is, words are never
75joined or hyphenated.
76.Pp
77The options are as follows:
78.Bl -tag -width indent
79.It Fl c
80Center the text, line by line.
81In this case, most of the other
82options are ignored; no splitting or joining of lines is done.
83.It Fl m
84Try to format mail header lines contained in the input sensibly.
85.It Fl n
86Format lines beginning with a
87.Ql \&.
88(dot) character.
89.It Fl p
90Allow indented paragraphs.
91Without the
92.Fl p
93flag, any change in the amount of whitespace at the start of a line
94results in a new paragraph being begun.
95.It Fl s
96Collapse whitespace inside lines, so that multiple whitespace
97characters are turned into a single space.
98(Or, at the end of a
99sentence, a double space.)
100.It Fl d Ar chars
101Treat the
102.Ar chars
103(and no others) as sentence-ending characters.
104By default the
105sentence-ending characters are full stop
106.Pq Ql \&. ,
107question mark
108.Pq Ql \&?
109and exclamation mark
110.Pq Ql \&! .
111Remember that some characters may need to be
112escaped to protect them from your shell.
113.It Fl l Ar number
114Replace multiple spaces with tabs at the start of each output
115line, if possible.
116Each
117.Ar number
118spaces will be replaced with one tab.
119The default is 8.
120If
121.Ar number
122is 0, spaces are preserved.
123.It Fl t Ar number
124Assume that the input files' tabs assume
125.Ar number
126spaces per tab stop.
127The default is 8.
128.El
129.Pp
130The
131.Nm
132utility
133is meant to format mail messages prior to sending, but may also be useful
134for other simple tasks.
135For instance,
136within visual mode of the
137.Xr ex 1
138editor (e.g.,
139.Xr vi 1 )
140the command
141.Pp
142.Dl \&!}fmt
143.Pp
144will reformat a paragraph,
145evening the lines.
146.Sh ENVIRONMENT
147The
148.Ev LANG , LC_ALL
149and
150.Ev LC_CTYPE
151environment variables affect the execution of
152.Nm
153as described in
154.Xr environ 7 .
155.Sh EXAMPLES
156Center the text in standard input:
157.Bd -literal -offset indent
158$ echo -e 'The merit of all things\enlies\enin their difficulty' | fmt -c
159                     The merit of all things
160                               lies
161                       in their difficulty
162.Ed
163.Pp
164Format the text in standard input collapsing spaces:
165.Bd -literal -offset indent
166$ echo -e 'Multiple   spaces    will be collapsed' | fmt -s
167Multiple spaces will be collapsed
168.Ed
169.Sh SEE ALSO
170.Xr fold 1 ,
171.Xr mail 1
172.Sh HISTORY
173The
174.Nm
175command appeared in
176.Bx 3 .
177.Pp
178The version described herein is a complete rewrite and appeared in
179.Fx 4.4 .
180.Sh AUTHORS
181.An Kurt Shoens
182.An Liz Allen
183(added
184.Ar goal
185length concept)
186.An Gareth McCaughan
187.Sh BUGS
188The program was designed to be simple and fast \- for more complex
189operations, the standard text processors are likely to be more appropriate.
190.Pp
191When the first line of an indented paragraph is very long (more than
192about twice the goal length), the indentation in the output can be
193wrong.
194.Pp
195The
196.Nm
197utility is not infallible in guessing what lines are mail headers and what
198lines are not.
199