61 lines
1.2 KiB
C
61 lines
1.2 KiB
C
/* head.c - copy first lines from input to stdout.
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*
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* Copyright 2006 Timothy Elliott <tle@holymonkey.com>
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*
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* See http://opengroup.org/onlinepubs/9699919799/utilities/head.html
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USE_HEAD(NEWTOY(head, "?n#<0=10", TOYFLAG_USR|TOYFLAG_BIN))
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config HEAD
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bool "head"
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default y
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help
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usage: head [-n number] [file...]
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Copy first lines from files to stdout. If no files listed, copy from
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stdin. Filename "-" is a synonym for stdin.
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-n Number of lines to copy.
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*/
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#define FOR_head
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#include "toys.h"
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GLOBALS(
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long lines;
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int file_no;
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)
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static void do_head(int fd, char *name)
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{
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int i, len, lines=TT.lines, size=sizeof(toybuf);
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if (toys.optc > 1) {
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// Print an extra newline for all but the first file
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if (TT.file_no++) xprintf("\n");
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xprintf("==> %s <==\n", name);
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xflush();
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}
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while (lines) {
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len = read(fd, toybuf, size);
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if (len<0) perror_msg_raw(name);
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if (len<1) break;
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for(i=0; i<len;) if (toybuf[i++] == '\n' && !--lines) break;
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xwrite(1, toybuf, i);
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}
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}
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void head_main(void)
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{
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char *arg = *toys.optargs;
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// handle old "-42" style arguments
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if (arg && *arg == '-' && arg[1]) {
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TT.lines = atolx(arg+1);
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toys.optc--;
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} else arg = 0;
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loopfiles(toys.optargs+!!arg, do_head);
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}
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