Implemented head(1).

    tried to mimic GNU behaviour.

1 files changed, 106 insertions, 0 deletions

diff --git a/head.c b/head.c
new file mode 100644
index 0000000..930839d
--- /dev/null
+++ b/head.c
@@ -0,0 +1,106 @@
+/*
+ * 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 $ */