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49 .TH HEAD 1 "Mar 4, 2013"
50 .SH NAME
51 head \- display first few lines of files
52 .SH SYNOPSIS
53 .SS "/usr/bin/head"
54 .LP
55 .nf
56 \fB/usr/bin/head\fR [\fB-q\fR] [\fB-v\fR] [\fB-number\fR ] [ \fB-n\fR \fInumber\fR ] [ \fB-c\fR \fInumber\fR] [\fIfilename\fR]...
57 .fi
59 .SS "ksh93"
60 .LP
61 .nf
62 \fBhead\fR [\fB-qv\fR] [\fB-n\fR \fIlines\fR] [\fB-c\fR \fIchars\fR] [\fB-s\fR \fIskip\fR] [\fIfilename\fR]...
63 .fi
65 .SH DESCRIPTION
66 .SS "/usr/bin/head"
67 .sp
68 .LP
69 The \fBhead\fR utility copies the first \fInumber\fR of lines of each
70 \fIfilename\fR to the standard output. If no \fIfilename\fR is given,
71 \fBhead\fR copies lines from the standard input. The default value of
72 \fInumber\fR is \fB10\fR lines. If \fB-c\fR is specified, \fBhead\fR
73 copies the first \fInumber\fR of bytes of each filename.
74 .sp
75 .LP
76 When more than one file is specified, the start of each file looks like:
77 .sp
78 .in +2
79 .nf
80 \fB==>\fR \fIfilename\fR \fB<==\fR
81 .fi
82 .in -2
84 .sp
85 .LP
86 Thus, a common way to display a set of short files, identifying each one, is:
87 .sp
88 .in +2
89 .nf
90 example% \fBhead -9999 filename1 filename2 ...\fR
91 .fi
92 .in -2
93 .sp
95 .SS "ksh93"
96 .sp
97 .LP
98 The \fBhead\fR built-in in \fBksh93\fR is associated with the \fB/bin\fR and
99 \fB/usr/bin\fR paths. It is invoked when \fBhead\fR is executed without a
100 pathname prefix and the pathname search finds a \fB/bin/head\fR or
101 \fB/usr/bin/head\fR executable.
102 .sp
103 .LP
104 \fBhead\fR copies one or more input files to standard output, stopping at a
105 designated point for each file or to the end of the file whichever comes first.
106 Copying ends at the point indicated by the options. By default, a header of the
107 form \fB==> filename <==\fR is output before all but the first file but this
108 can be changed with the \fB-q\fR and \fB-v\fR options. If no file is given, or
109 if the file is \fB-\fR, \fBhead\fR copies from standard input starting at the
110 current location.
111 .sp
112 .LP
113 The option argument for \fB-c\fR and \fB-s\fR can optionally be followed by one
114 of the following characters to specify a different unit other than a single
115 byte:
116 .sp
117 .ne 2
118 .na
119 \fB\fBb\fR\fR
120 .ad
121 .RS 5n
122 512 bytes
123 .RE
125 .sp
126 .ne 2
127 .na
128 \fB\fBk\fR\fR
129 .ad
130 .RS 5n
131 1-kilobyte
132 .RE
134 .sp
135 .ne 2
136 .na
137 \fB\fBm\fR\fR
138 .ad
139 .RS 5n
140 1-megabyte
141 .RE
143 .sp
144 .LP
145 For backwards compatibility, \fB-number\fR is equivalent to \fB-n\fR number.
146 .SH OPTIONS
147 .SS "/usr/bin/head"
148 .sp
149 .LP
150 The following options are supported by \fB/usr/bin/head\fR:
151 .sp
152 .ne 2
153 .na
154 \fB\fB-n\fR \fInumber\fR\fR
155 .ad
156 .RS 13n
157 The first \fInumber\fR lines of each input file is copied to standard output.
158 The \fInumber\fR option-argument must be a positive decimal integer.
159 .RE
161 .sp
162 .ne 2
163 .na
164 \fB\fB-c\fR \fInumber\fR\fR
165 .ad
166 .RS 13n
167 The first \fInumber\fR bytes of each input file is copied to standard output.
168 The \fInumber\fR option-argument must be a positive decimal integer. Note,
169 output may end in the middle of a character if a file contains multi-byte
170 characters.
171 .RE
173 .sp
174 .ne 2
175 .na
176 \fB\fB-\fR\fInumber\fR\fR
177 .ad
178 .RS 13n
179 The \fInumber\fR argument is a positive decimal integer with the same effect as
180 the \fB-n\fR \fInumber\fR option.
181 .RE
183 .sp
184 .ne 2
185 .na
186 \fB-q\fR
187 .ad
188 .RS 13n
189 \fBhead\fR will not print a header in between each specified file.
190 .RE
192 .sp
193 .ne 2
194 .na
195 \fB-v\fR
196 .ad
197 .RS 13n
198 \fBhead\fR will always print a header in between each specified file.
199 .RE
201 .sp
202 .LP
203 If no options are specified, \fBhead\fR acts as if \fB-n\fR \fB10\fR had been
204 specified.
205 .SS "ksh93"
206 .sp
207 .LP
208 The following options are supported by the head built-in command in
209 \fBksh93\fR:
210 .sp
211 .ne 2
212 .na
213 \fB\fB-n\fR\fR
214 .ad
215 .br
216 .na
217 \fB\fB--lines=\fR\fIlines\fR\fR
218 .ad
219 .RS 18n
220 Copy lines from each file. The default value is \fB10\fR.
221 .RE
223 .sp
224 .ne 2
225 .na
226 \fB\fB-c\fR\fR
227 .ad
228 .br
229 .na
230 \fB\fB--bytes=\fR\fIchars\fR\fR
231 .ad
232 .RS 18n
233 Copy \fIchars\fR bytes from each file.
234 .RE
236 .sp
237 .ne 2
238 .na
239 \fB\fB-q\fR\fR
240 .ad
241 .br
242 .na
243 \fB\fB--quiet|silent\fR\fR
244 .ad
245 .RS 18n
246 Never output filename headers.
247 .RE
249 .sp
250 .ne 2
251 .na
252 \fB\fB-s\fR\fR
253 .ad
254 .br
255 .na
256 \fB\fB--skip=\fR\fIskip\fR\fR
257 .ad
258 .RS 18n
259 Skip \fIskip\fR characters or lines from each file before copying.
260 .RE
262 .sp
263 .ne 2
264 .na
265 \fB\fB-v\fR\fR
266 .ad
267 .br
268 .na
269 \fB\fB--verbose\fR\fR
270 .ad
271 .RS 18n
272 Always output filename headers.
273 .RE
275 .SH OPERANDS
276 .sp
277 .LP
278 The following operand is supported:
279 .sp
280 .ne 2
281 .na
282 \fB\fB\fIfilename\fR\fR\fR
283 .ad
284 .RS 12n
285 A path name of an input file. If no \fIfile\fR operands are specified, the
286 standard input is used.
287 .RE
289 .SH EXAMPLES
290 .LP
291 \fBExample 1 \fRWriting the First Ten Lines of All Files
292 .sp
293 .LP
294 The following example writes the first ten lines of all files, except those
295 with a leading period, in the directory:
297 .sp
298 .in +2
299 .nf
300 example% \fBhead *\fR
301 .fi
302 .in -2
303 .sp
305 .SH ENVIRONMENT VARIABLES
306 .sp
307 .LP
308 See \fBenviron\fR(5) for descriptions of the following environment variables
309 that affect the execution of \fBhead\fR: \fBLANG\fR, \fBLC_ALL\fR,
310 \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
311 .SH EXIT STATUS
312 .sp
313 .LP
314 The following exit values are returned:
315 .sp
316 .ne 2
317 .na
318 \fB\fB0\fR\fR
319 .ad
320 .RS 6n
321 Successful completion.
322 .RE
324 .sp
325 .ne 2
326 .na
327 \fB\fB>0\fR\fR
328 .ad
329 .RS 6n
330 An error occurred.
331 .RE
333 .SH ATTRIBUTES
334 .sp
335 .LP
336 See \fBattributes\fR(5) for descriptions of the following attributes:
337 .SS "/usr/bin/head"
338 .sp
340 .sp
341 .TS
342 box;
343 c | c
344 l | l .
345 ATTRIBUTE TYPE ATTRIBUTE VALUE
346 _
347 CSI Enabled
348 _
349 Interface Stability Committed
350 _
351 Standard See \fBstandards\fR(5).
352 .TE
354 .SS "ksh93"
355 .sp
357 .sp
358 .TS
359 box;
360 c | c
361 l | l .
362 ATTRIBUTE TYPE ATTRIBUTE VALUE
363 _
364 Interface Stability See below.
365 .TE
367 .sp
368 .LP
369 The \fBksh93\fR built-in binding to \fB/bin\fR and \fB/usr/bin\fR is Volatile.
370 The built-in interfaces are Uncommitted.
371 .SH SEE ALSO
372 .sp
373 .LP
374 \fBcat\fR(1), \fBksh93\fR(1), \fBmore\fR(1), \fBpg\fR(1), \fBtail\fR(1),
375 \fBattributes\fR(5), \fBenviron\fR(5), \fBstandards\fR(5)