1da2e3ebdSchin /***********************************************************************
2da2e3ebdSchin * *
3da2e3ebdSchin * This software is part of the ast package *
4*d6f391efSAndy Fiddaman * Copyright (c) 1992-2013 AT&T Intellectual Property *
5da2e3ebdSchin * and is licensed under the *
6b30d1939SAndy Fiddaman * Eclipse Public License, Version 1.0 *
77c2fbfb3SApril Chin * by AT&T Intellectual Property *
8da2e3ebdSchin * *
9da2e3ebdSchin * A copy of the License is available at *
10b30d1939SAndy Fiddaman * http://www.eclipse.org/org/documents/epl-v10.html *
11b30d1939SAndy Fiddaman * (with md5 checksum b35adb5213ca9657e911e9befb180842) *
12da2e3ebdSchin * *
13da2e3ebdSchin * Information and Software Systems Research *
14da2e3ebdSchin * AT&T Research *
15da2e3ebdSchin * Florham Park NJ *
16da2e3ebdSchin * *
17*d6f391efSAndy Fiddaman * Glenn Fowler <glenn.s.fowler@gmail.com> *
18*d6f391efSAndy Fiddaman * David Korn <dgkorn@gmail.com> *
19da2e3ebdSchin * *
20da2e3ebdSchin ***********************************************************************/
21da2e3ebdSchin #pragma prototyped
22da2e3ebdSchin /*
23da2e3ebdSchin * David Korn
24da2e3ebdSchin * AT&T Bell Laboratories
25da2e3ebdSchin *
26da2e3ebdSchin * output the beginning portion of one or more files
27da2e3ebdSchin */
28da2e3ebdSchin
29da2e3ebdSchin static const char usage[] =
30*d6f391efSAndy Fiddaman "[-n?\n@(#)$Id: head (AT&T Research) 2013-09-19 $\n]"
31da2e3ebdSchin USAGE_LICENSE
32da2e3ebdSchin "[+NAME?head - output beginning portion of one or more files ]"
33da2e3ebdSchin "[+DESCRIPTION?\bhead\b copies one or more input files to standard "
34da2e3ebdSchin "output stopping at a designated point for each file or to the end of "
35da2e3ebdSchin "the file whichever comes first. Copying ends at the point indicated by "
36da2e3ebdSchin "the options. By default a header of the form \b==> \b\afilename\a\b "
37da2e3ebdSchin "<==\b is output before all but the first file but this can be changed "
38da2e3ebdSchin "with the \b-q\b and \b-v\b options.]"
39da2e3ebdSchin "[+?If no \afile\a is given, or if the \afile\a is \b-\b, \bhead\b "
40da2e3ebdSchin "copies from standard input starting at the current location.]"
41da2e3ebdSchin "[+?The option argument for \b-c\b, and \b-s\b can optionally be "
42da2e3ebdSchin "followed by one of the following characters to specify a different unit "
43da2e3ebdSchin "other than a single byte:]"
44da2e3ebdSchin "{"
45da2e3ebdSchin "[+b?512 bytes.]"
46da2e3ebdSchin "[+k?1-killobyte.]"
47da2e3ebdSchin "[+m?1-megabyte.]"
48da2e3ebdSchin "}"
49da2e3ebdSchin "[+?For backwards compatibility, \b-\b\anumber\a is equivalent to \b-n\b "
50da2e3ebdSchin "\anumber\a.]"
51da2e3ebdSchin "[n:lines?Copy \alines\a lines from each file.]#[lines:=10]"
52da2e3ebdSchin "[c:bytes?Copy \achars\a bytes from each file.]#[chars]"
53da2e3ebdSchin "[q:quiet|silent?Never ouput filename headers.]"
54da2e3ebdSchin "[s:skip?Skip \askip\a characters or lines from each file before "
55da2e3ebdSchin "copying.]#[skip]"
56da2e3ebdSchin "[v:verbose?Always ouput filename headers.]"
57da2e3ebdSchin "\n\n"
58da2e3ebdSchin "[ file ... ]"
59da2e3ebdSchin "\n\n"
60da2e3ebdSchin "[+EXIT STATUS?]"
61da2e3ebdSchin "{"
62da2e3ebdSchin "[+0?All files copied successfully.]"
63da2e3ebdSchin "[+>0?One or more files did not copy.]"
64da2e3ebdSchin "}"
65da2e3ebdSchin "[+SEE ALSO?\bcat\b(1), \btail\b(1)]"
66da2e3ebdSchin ;
67da2e3ebdSchin
68da2e3ebdSchin #include <cmd.h>
69da2e3ebdSchin
70da2e3ebdSchin int
b_head(int argc,register char ** argv,Shbltin_t * context)71b30d1939SAndy Fiddaman b_head(int argc, register char** argv, Shbltin_t* context)
72da2e3ebdSchin {
73da2e3ebdSchin static const char header_fmt[] = "\n==> %s <==\n";
74da2e3ebdSchin
75da2e3ebdSchin register Sfio_t* fp;
76da2e3ebdSchin register char* cp;
77da2e3ebdSchin register off_t keep = 10;
78da2e3ebdSchin register off_t skip = 0;
79da2e3ebdSchin register int delim = '\n';
80*d6f391efSAndy Fiddaman off_t moved;
81da2e3ebdSchin int header = 1;
82da2e3ebdSchin char* format = (char*)header_fmt+1;
83da2e3ebdSchin
84da2e3ebdSchin cmdinit(argc, argv, context, ERROR_CATALOG, 0);
85da2e3ebdSchin for (;;)
86da2e3ebdSchin {
87da2e3ebdSchin switch (optget(argv, usage))
88da2e3ebdSchin {
89da2e3ebdSchin case 'c':
90da2e3ebdSchin delim = -1;
91da2e3ebdSchin /*FALLTHROUGH*/
92da2e3ebdSchin case 'n':
93da2e3ebdSchin if (opt_info.offset && argv[opt_info.index][opt_info.offset] == 'c')
94da2e3ebdSchin {
95da2e3ebdSchin delim = -1;
96da2e3ebdSchin opt_info.offset++;
97da2e3ebdSchin }
98da2e3ebdSchin if ((keep = opt_info.number) <=0)
99da2e3ebdSchin error(2, "%s: %I*d: positive numeric option argument expected", opt_info.name, sizeof(keep), keep);
100da2e3ebdSchin continue;
101da2e3ebdSchin case 'q':
102da2e3ebdSchin header = argc;
103da2e3ebdSchin continue;
104da2e3ebdSchin case 'v':
105da2e3ebdSchin header = 0;
106da2e3ebdSchin continue;
107da2e3ebdSchin case 's':
108da2e3ebdSchin skip = opt_info.number;
109da2e3ebdSchin continue;
110da2e3ebdSchin case '?':
111da2e3ebdSchin error(ERROR_usage(2), "%s", opt_info.arg);
112da2e3ebdSchin continue;
113da2e3ebdSchin case ':':
114da2e3ebdSchin error(2, "%s", opt_info.arg);
115da2e3ebdSchin continue;
116da2e3ebdSchin }
117da2e3ebdSchin break;
118da2e3ebdSchin }
119da2e3ebdSchin argv += opt_info.index;
120da2e3ebdSchin argc -= opt_info.index;
121da2e3ebdSchin if (error_info.errors)
122da2e3ebdSchin error(ERROR_usage(2), "%s", optusage(NiL));
123da2e3ebdSchin if (cp = *argv)
124da2e3ebdSchin argv++;
125da2e3ebdSchin do
126da2e3ebdSchin {
127da2e3ebdSchin if (!cp || streq(cp, "-"))
128da2e3ebdSchin {
129da2e3ebdSchin cp = "/dev/stdin";
130da2e3ebdSchin fp = sfstdin;
131da2e3ebdSchin sfset(fp, SF_SHARE, 1);
132da2e3ebdSchin }
133da2e3ebdSchin else if (!(fp = sfopen(NiL, cp, "r")))
134da2e3ebdSchin {
135da2e3ebdSchin error(ERROR_system(0), "%s: cannot open", cp);
136da2e3ebdSchin continue;
137da2e3ebdSchin }
138da2e3ebdSchin if (argc > header)
139da2e3ebdSchin sfprintf(sfstdout, format, cp);
140da2e3ebdSchin format = (char*)header_fmt;
141da2e3ebdSchin if (skip > 0)
142*d6f391efSAndy Fiddaman {
143*d6f391efSAndy Fiddaman if ((moved = sfmove(fp, NiL, skip, delim)) < 0 && !ERROR_PIPE(errno) && errno != EINTR)
144*d6f391efSAndy Fiddaman error(ERROR_system(0), "%s: skip error", cp);
145*d6f391efSAndy Fiddaman if (delim >= 0 && moved < skip)
146*d6f391efSAndy Fiddaman goto next;
147*d6f391efSAndy Fiddaman }
148*d6f391efSAndy Fiddaman if ((moved = sfmove(fp, sfstdout, keep, delim)) < 0 && !ERROR_PIPE(errno) && errno != EINTR ||
149*d6f391efSAndy Fiddaman delim >= 0 && moved < keep && sfmove(fp, sfstdout, SF_UNBOUND, -1) < 0 && !ERROR_PIPE(errno) && errno != EINTR)
150da2e3ebdSchin error(ERROR_system(0), "%s: read error", cp);
151*d6f391efSAndy Fiddaman next:
152da2e3ebdSchin if (fp != sfstdin)
153da2e3ebdSchin sfclose(fp);
154da2e3ebdSchin } while (cp = *argv++);
155da2e3ebdSchin if (sfsync(sfstdout))
156da2e3ebdSchin error(ERROR_system(0), "write error");
157da2e3ebdSchin return error_info.errors != 0;
158da2e3ebdSchin }
159