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-rw-r--r--toys/posix/head.c61
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+/* 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#<0=10", 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++) xprintf("\n");
+ xprintf("==> %s <==\n", name);
+ xflush();
+ }
+
+ while (lines) {
+ 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;)
+ if (toybuf[i++] == '\n' && !--lines) break;
+
+ xwrite(1, toybuf, i);
+ }
+}
+
+void head_main(void)
+{
+ loopfiles(toys.optargs, do_head);
+}