Implement head

diff --git a/toys/head.c b/toys/head.c
new file mode 100644 (file)
index 0000000..8f0baa2
--- /dev/null
+++ b/toys/head.c
@@ -0,0 +1,62 @@
+/* vi: set sw=4 ts=4:
+ *
+ * head.c - copy first lines from input to stdout.
+ *
+ * Copyright 2006 Timothy Elliott <tle@holymonkey.com>
+ *
+ * See http://www.opengroup.org/onlinepubs/009695399/utilities/head.html
+
+USE_HEAD(NEWTOY(head, "n#", TOYFLAG_BIN))
+
+config HEAD
+       bool "head"
+       default y
+       help
+         usage: head [-n number] [file...]
+         Copy first lines from files to stdout. If no files listed, copy from
+         stdin. Filename "-" is a synonym for stdin.
+
+         -n    Number of lines to copy.
+*/
+
+#include "toys.h"
+
+DEFINE_GLOBALS(
+       long lines;
+       int file_no;
+)
+
+#define TT this.head
+
+static void do_head(int fd, char *name)
+{
+       int i, len, lines=TT.lines, size=sizeof(toybuf);
+
+       if (toys.optc > 1) {
+               // Print an extra newline for all but the first file
+               if (TT.file_no++ > 0) printf("\n");
+               printf("==> %s <==\n", name);
+       }
+
+       for (;lines>0;) {
+               len = read(fd, toybuf, size);
+               if (len<0) {
+                       perror_msg("%s",name);
+                       toys.exitval = EXIT_FAILURE;
+               }
+               if (len<1) break;
+               
+               for(i=0; i<len; i++) {
+                       if (toybuf[i] == '\n' && --lines < 1) break;
+               }
+               xwrite(1, toybuf, i+1);
+       }
+}
+
+void head_main(void)
+{
+       if (!toys.optflags) TT.lines = 10;
+       if (TT.lines < 0) perror_exit("Invalid number of lines.");
+       TT.file_no = 0;
+       loopfiles(toys.optargs, do_head);
+}

diff --git a/toys/nice.c b/toys/nice.c
index 2fda267..fa059bb 100644 (file)
--- a/toys/nice.c
+++ b/toys/nice.c
@@ -24,8 +24,6 @@ config NICE
 
 #include "toys.h"
 
-// Hello doesn't use these globals, they're here for example/skeleton purposes.
-
 DEFINE_GLOBALS(
        long priority;
 )