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authorJohn Beppu1999-12-10 07:42:50 +0000
committerJohn Beppu1999-12-10 07:42:50 +0000
commit3157b1fba9ee8a558b04e9025da9f77e4256c0ea (patch)
tree27ea10d69773a06c8618132a2b76e7583db9da9c /coreutils/head.c
parenta3e0d7928b0042dfe1be94da62b750664306b404 (diff)
downloadbusybox-3157b1fba9ee8a558b04e9025da9f77e4256c0ea.zip
busybox-3157b1fba9ee8a558b04e9025da9f77e4256c0ea.tar.gz
Implemented head(1).
tried to mimic GNU behaviour.
Diffstat (limited to 'coreutils/head.c')
-rw-r--r--coreutils/head.c106
1 files changed, 106 insertions, 0 deletions
diff --git a/coreutils/head.c b/coreutils/head.c
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+++ b/coreutils/head.c
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+/*
+ * Mini head implementation for busybox
+ *
+ *
+ * Copyright (C) 1999 by Lineo, inc.
+ * Written by John Beppu <beppu@line.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#include "internal.h"
+#include <errno.h>
+#include <stdio.h>
+
+const char head_usage[] =
+"Usage: head [OPTION]... [FILE]...\n"
+"Print first 10 lines of each FILE to standard output.\n"
+"With more than one FILE, precede each with a header giving the file name.\n"
+"With no FILE, or when FILE is -, read standard input.\n\n"
+" -h display this help and exit\n";
+
+int
+head(int len, FILE *src)
+{
+ int i;
+ char buffer[1024];
+
+ for (i = 0; i < len; i++) {
+ fgets(buffer, 1024, src);
+ if (feof(src)) { break; }
+ fputs(buffer, stdout);
+ }
+ return 0;
+}
+
+/* BusyBoxed head(1) */
+int
+head_main(int argc, char **argv)
+{
+ int i = 1;
+ char opt;
+ int len = 10;
+
+ /* 1st option is potentially special */
+ if ((argv[1][0] == '-') && isDecimal(argv[1][1])) {
+ int tmplen = atoi(&argv[1][1]);
+ if (tmplen) { len = tmplen; }
+ i = 2;
+ }
+
+ /* parse argv[] */
+ for ( ; i < argc; i++) {
+ if (argv[i][0] == '-') {
+ opt = argv[i][1];
+ switch (opt) {
+ case 'h':
+ usage(head_usage);
+ default:
+ fprintf(stderr, "head: invalid option -- %c\n", opt);
+ usage(head_usage);
+ }
+ } else {
+ break;
+ }
+ }
+
+ /* get rest of argv[] or stdin if nothing's left */
+ if (i >= argc) {
+ head(len, stdin);
+
+ } else {
+ int need_headers = ((argc - i) > 1);
+ for ( ; i < argc; i++) {
+ FILE *src;
+ src = fopen(argv[i], "r");
+ if (!src) {
+ fprintf(stderr,"head: %s: %s\n", argv[i], strerror(errno));
+ } else {
+ /* emulating GNU behaviour */
+ if (need_headers) {
+ fprintf(stdout, "==> %s <==\n", argv[i]);
+ }
+ head(len, src);
+ if (i < argc - 1) {
+ fprintf(stdout, "\n");
+ }
+ }
+ }
+ }
+ exit(0);
+}
+
+/* $Id: head.c,v 1.1 1999/12/10 07:42:50 beppu Exp $ */