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Diffstat (limited to 'toys/posix/head.c')
-rw-r--r-- | toys/posix/head.c | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/toys/posix/head.c b/toys/posix/head.c new file mode 100644 index 00000000..1d1e54a3 --- /dev/null +++ b/toys/posix/head.c @@ -0,0 +1,61 @@ +/* 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); +} |