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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1992-2010 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* David Korn
* AT&T Bell Laboratories
*
* output the beginning portion of one or more files
*/
static const char usage[] =
"[-n?\n@(#)$Id: head (AT&T Research) 2006-09-27 $\n]"
USAGE_LICENSE
"[+NAME?head - output beginning portion of one or more files ]"
"[+DESCRIPTION?\bhead\b copies one or more input files to standard "
"output stopping at a designated point for each file or to the end of "
"the file whichever comes first. Copying ends at the point indicated by "
"the options. By default a header of the form \b==> \b\afilename\a\b "
"<==\b is output before all but the first file but this can be changed "
"with the \b-q\b and \b-v\b options.]"
"[+?If no \afile\a is given, or if the \afile\a is \b-\b, \bhead\b "
"copies from standard input starting at the current location.]"
"[+?The option argument for \b-c\b, and \b-s\b can optionally be "
"followed by one of the following characters to specify a different unit "
"other than a single byte:]"
"{"
"[+b?512 bytes.]"
"[+k?1-killobyte.]"
"[+m?1-megabyte.]"
"}"
"[+?For backwards compatibility, \b-\b\anumber\a is equivalent to \b-n\b "
"\anumber\a.]"
"[n:lines?Copy \alines\a lines from each file.]#[lines:=10]"
"[c:bytes?Copy \achars\a bytes from each file.]#[chars]"
"[q:quiet|silent?Never ouput filename headers.]"
"[s:skip?Skip \askip\a characters or lines from each file before "
"copying.]#[skip]"
"[v:verbose?Always ouput filename headers.]"
"\n\n"
"[ file ... ]"
"\n\n"
"[+EXIT STATUS?]"
"{"
"[+0?All files copied successfully.]"
"[+>0?One or more files did not copy.]"
"}"
"[+SEE ALSO?\bcat\b(1), \btail\b(1)]"
;
#include <cmd.h>
int
b_head(int argc, register char** argv, void* context)
{
static const char header_fmt[] = "\n==> %s <==\n";
register Sfio_t* fp;
register char* cp;
register off_t keep = 10;
register off_t skip = 0;
register int delim = '\n';
int header = 1;
char* format = (char*)header_fmt+1;
cmdinit(argc, argv, context, ERROR_CATALOG, 0);
for (;;)
{
switch (optget(argv, usage))
{
case 'c':
delim = -1;
/*FALLTHROUGH*/
case 'n':
if (opt_info.offset && argv[opt_info.index][opt_info.offset] == 'c')
{
delim = -1;
opt_info.offset++;
}
if ((keep = opt_info.number) <=0)
error(2, "%s: %I*d: positive numeric option argument expected", opt_info.name, sizeof(keep), keep);
continue;
case 'q':
header = argc;
continue;
case 'v':
header = 0;
continue;
case 's':
skip = opt_info.number;
continue;
case '?':
error(ERROR_usage(2), "%s", opt_info.arg);
continue;
case ':':
error(2, "%s", opt_info.arg);
continue;
}
break;
}
argv += opt_info.index;
argc -= opt_info.index;
if (error_info.errors)
error(ERROR_usage(2), "%s", optusage(NiL));
if (cp = *argv)
argv++;
do
{
if (!cp || streq(cp, "-"))
{
cp = "/dev/stdin";
fp = sfstdin;
sfset(fp, SF_SHARE, 1);
}
else if (!(fp = sfopen(NiL, cp, "r")))
{
error(ERROR_system(0), "%s: cannot open", cp);
continue;
}
if (argc > header)
sfprintf(sfstdout, format, cp);
format = (char*)header_fmt;
if (skip > 0)
sfmove(fp, NiL, skip, delim);
if (sfmove(fp, sfstdout, keep, delim) < 0 && errno != EPIPE)
error(ERROR_system(0), "%s: read error", cp);
if (fp != sfstdin)
sfclose(fp);
} while (cp = *argv++);
if (sfsync(sfstdout))
error(ERROR_system(0), "write error");
return error_info.errors != 0;
}
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