xref: /netbsd/usr.bin/xargs/xargs.1 (revision c4a72b64)
1.\"	$NetBSD: xargs.1,v 1.16 2002/10/02 10:09:51 wiz Exp $
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38.\"	@(#)xargs.1	8.1 (Berkeley) 6/6/93
39.\"
40.Dd December 21, 1999
41.Dt XARGS 1
42.Os
43.Sh NAME
44.Nm xargs
45.Nd "construct argument list(s) and execute utility"
46.Sh SYNOPSIS
47.Nm
48.Op Fl 0
49.Op Fl p
50.Op Fl t
51.Oo Op Fl x
52.Fl n Ar number
53.Oc
54.Op Fl s Ar size
55.Op Ar utility Op Ar arguments ...
56.Sh DESCRIPTION
57The
58.Nm
59utility reads space, tab, newline and end-of-file delimited arguments
60from the standard input and executes the specified
61.Ar utility
62with them as arguments.
63.Pp
64The utility and any arguments specified on the command line are given
65to the
66.Ar utility
67upon each invocation, followed by some number of the arguments read
68from standard input.
69The
70.Ar utility
71is repeatedly executed until standard input is exhausted.
72.Pp
73Spaces, tabs and newlines may be embedded in arguments using single
74(``\ '\ '')
75or double (``"'') quotes or backslashes (``\e'').
76Single quotes escape all non-single quote characters, excluding newlines,
77up to the matching single quote.
78Double quotes escape all non-double quote characters, excluding newlines,
79up to the matching double quote.
80Any single character, including newlines, may be escaped by a backslash.
81.Pp
82The options are as follows:
83.Bl -tag -width Fl
84.It Fl 0
85Use NUL
86(``\e0'')
87instead of whitespace as the argument separator.
88This can be used in conjunction with the
89.Fl print0
90option of
91.Xr find 1 .
92.It Fl n Ar number
93Set the maximum number of arguments taken from standard input for each
94invocation of the utility.
95An invocation of
96.Ar utility
97will use less than
98.Ar number
99standard input arguments if the number of bytes accumulated (see the
100.Fl s
101option) exceeds the specified
102.Ar size
103or there are fewer than
104.Ar number
105arguments remaining for the last invocation of
106.Ar utility .
107The current default value for
108.Ar number
109is 5000.
110.It Fl p
111Prompt mode: immediately before each command execution the user is prompted
112whether to execute the command instance.
113If an affirmative response is read from
114.Pa /dev/tty
115the command will be executed; otherwise this particular invocation will be
116skipped.
117This option implies the
118.Fl t
119option.
120.It Fl s Ar size
121Set the maximum number of bytes for the command line length provided to
122.Ar utility .
123The sum of the length of the utility name and the arguments passed to
124.Ar utility
125(including
126.Dv NULL
127terminators) will be less than or equal to this number.
128The current default value for
129.Ar size
130is
131.Dv ARG_MAX
132- 4096.
133.It Fl t
134Echo the command to be executed to standard error immediately before it
135is executed.
136.It Fl x
137Force
138.Nm
139to terminate immediately if a command line containing
140.Ar number
141arguments will not fit in the specified (or default) command line length.
142.El
143.Pp
144If no
145.Ar utility
146is specified,
147.Xr echo 1
148is used.
149.Pp
150Undefined behavior may occur if
151.Ar utility
152reads from the standard input.
153.Pp
154The
155.Nm
156utility exits immediately (without processing any further input) if a
157command line cannot be assembled,
158.Ar utility
159cannot be invoked, an invocation of the utility is terminated by a signal
160or an invocation of the utility exits with a value of 255.
161.Sh EXIT STATUS
162.Nm
163exits with one of the following values:
164.Bl -tag -width Ds -compact
165.It 0
166All invocations of
167.Ar utility
168returned a zero exit status.
169.It 123
170One or more invocations of
171.Ar utility
172returned a nonzero exit status.
173.It 124
174The
175.Ar utility
176exited with a 255 exit status.
177.It 125
178The
179.Ar utility
180was killed or stopped by a signal.
181.It 126
182The
183.Ar utility
184was found but could not be invoked.
185.It 127
186The
187.Ar utility
188could not be found.
189.It 1
190Some other error occurred.
191.El
192.Sh FILES
193.Bl -tag -width /dev/tty -compact
194.It Pa /dev/tty
195used to read responses in prompt mode
196.El
197.Sh SEE ALSO
198.Xr echo 1 ,
199.Xr find 1
200.Sh STANDARDS
201The
202.Nm
203utility is expected to be
204.St -p1003.2
205compliant.
206.Sh HISTORY
207The
208.Nm xargs
209command appeared in PWB Unix 1.0.
210It made its first BSD appearance in the 4.3 Reno release.
211.Pp
212The meaning of 123, 124, and 125 exit values and the
213.Fl 0
214option were taken from GNU xargs.
215