add head

Makefile

@@ -1,8 +1,8 @@
 include config.mk
 
 LIB = util/enmasse.o util/eprintf.o util/recurse.o
-SRC = basename.c cat.c chown.c date.c dirname.c echo.c false.c grep.c ln.c \
-      mkfifo.c pwd.c rm.c sleep.c tee.c touch.c true.c wc.c
+SRC = basename.c cat.c chown.c date.c dirname.c echo.c false.c grep.c head.c \
+      ln.c mkfifo.c pwd.c rm.c sleep.c tee.c touch.c true.c wc.c
 OBJ = $(SRC:.c=.o) $(LIB)
 BIN = $(SRC:.c=)
 MAN = $(SRC:.c=.1)

chown.c

@@ -49,7 +49,7 @@ main(int argc, char *argv[])
 		if(errno != 0)
 			eprintf("getgrnam %s:", group);
 		else if(!gr)
-			eprintf("getgrnam %s: no such user\n", group);
+			eprintf("getgrnam %s: no such group\n", group);
 	}
 	for(; optind < argc; optind++)
 		chownpwgr(argv[optind]);

date.c

@@ -8,7 +8,7 @@
 int
 main(int argc, char *argv[])
 {
-	char buf[BUFSIZ], c;
+	char buf[BUFSIZ], c, *end;
 	char *fmt = "%c";
 	struct tm *now = NULL;
 	time_t t;
@@ -17,7 +17,9 @@ main(int argc, char *argv[])
 	while((c = getopt(argc, argv, "d:")) != -1)
 		switch(c) {
 		case 'd':
-			t = strtol(optarg, NULL, 0);
+			t = strtol(optarg, &end, 0);
+			if(*end != '\0')
+				eprintf("%s: not a number\n", optarg);
 			break;
 		default:
 			exit(EXIT_FAILURE);

head.1

@@ -0,0 +1,15 @@
+.TH HEAD 1 sbase\-VERSION
+.SH NAME
+head \- output first part of files
+.SH SYNOPSIS
+.B head
+.RB [ \-n
+.IR lines ]
+.RI [ file ...]
+.SH DESCRIPTION
+.B head
+writes the first 10 lines of each file to stdout.
+.SH OPTIONS
+.TP
+.BI \-n " lines"
+outputs the given number of lines.

head.c

@@ -0,0 +1,47 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "util.h"
+
+static void head(FILE *, const char *, long);
+
+int
+main(int argc, char *argv[])
+{
+	char *end, c;
+	long n = 10;
+	FILE *fp;
+
+	while((c = getopt(argc, argv, "n:")) != -1)
+		switch(c) {
+		case 'n':
+			n = strtol(optarg, &end, 0);
+			if(*end != '\0')
+				eprintf("%s: not a number\n", optarg);
+			break;
+		default:
+			exit(EXIT_FAILURE);
+		}
+	if(optind == argc)
+		head(stdin, "<stdin>", n);
+	else for(; optind < argc; optind++) {
+		if(!(fp = fopen(argv[optind], "r")))
+			eprintf("fopen %s:", argv[optind]);
+		head(fp, argv[optind], n);
+		fclose(fp);
+	}
+	return EXIT_SUCCESS;
+}
+
+void
+head(FILE *fp, const char *str, long n)
+{
+	char buf[BUFSIZ];
+	int i;
+
+	for(i = 0; i < n && fgets(buf, sizeof buf, fp); i++)
+		fputs(buf, stdout);
+	if(ferror(fp))
+		eprintf("%s: read error:", str);
+}

sleep.c

@@ -6,6 +6,7 @@
 int
 main(int argc, char *argv[])
 {
+	char *end;
 	unsigned int seconds;
 
 	if(getopt(argc, argv, "") != -1)
@@ -13,7 +14,9 @@ main(int argc, char *argv[])
 	if(optind != argc-1)
 		eprintf("usage: %s seconds\n", argv[0]);
 
-	seconds = atoi(argv[optind]);
+	seconds = strtol(argv[optind], &end, 0);
+	if(*end != '\0')
+		eprintf("%s: not a number\n", argv[optind]);
 	while((seconds = sleep(seconds)) > 0)
 		;
 	return EXIT_SUCCESS;

touch.c

@@ -17,7 +17,7 @@ static time_t t;
 int
 main(int argc, char *argv[])
 {
-	char c;
+	char *end, c;
 
 	t = time(NULL);
 	while((c = getopt(argc, argv, "ct:")) != -1)
@@ -26,7 +26,9 @@ main(int argc, char *argv[])
 			cflag = true;
 			break;
 		case 't':
-			t = strtol(optarg, NULL, 0);
+			t = strtol(optarg, &end, 0);
+			if(*end != '\0')
+				eprintf("%s: not a number\n", optarg);
 			break;
 		default:
 			exit(EXIT_FAILURE);