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authorTimothy Elliott <tle@holymonkey.com>2012-02-06 17:35:59 -0800
committerTimothy Elliott <tle@holymonkey.com>2012-02-06 17:35:59 -0800
commit41a2130487e6096ec9f3cecbfc90f4c2d0169ec1 (patch)
tree99c24d2c034baee0436bfa6393ba2d10ae4569e8 /toys/head.c
parent5e6dca62869816709f4f6a16d9c191a9e93522a4 (diff)
downloadtoybox-41a2130487e6096ec9f3cecbfc90f4c2d0169ec1.tar.gz
Implement head
Diffstat (limited to 'toys/head.c')
-rw-r--r--toys/head.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/toys/head.c b/toys/head.c
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--- /dev/null
+++ b/toys/head.c
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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#", 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);
+}