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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);
}
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