Mercurial > hg > toybox
changeset 444:d3ca5e15e457
Implement head
author | Timothy Elliott <tle@holymonkey.com> |
---|---|
date | Mon, 06 Feb 2012 17:35:59 -0800 |
parents | 41b5ac08208f |
children | 2c47a9c0c619 |
files | toys/head.c toys/nice.c |
diffstat | 2 files changed, 62 insertions(+), 2 deletions(-) [+] |
line wrap: on
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toys/head.c Mon Feb 06 17:35:59 2012 -0800 @@ -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); +}