| /* head.c - copy first lines from input to stdout. |
| * |
| * Copyright 2006 Timothy Elliott <tle@holymonkey.com> |
| * |
| * See http://opengroup.org/onlinepubs/9699919799/utilities/head.html |
| |
| USE_HEAD(NEWTOY(head, "?n#<0=10qv", TOYFLAG_USR|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 |
| -q Never print headers |
| -v Always print headers |
| */ |
| |
| #define FOR_head |
| #include "toys.h" |
| |
| GLOBALS( |
| long lines; |
| int file_no; |
| ) |
| |
| static void do_head(int fd, char *name) |
| { |
| int i, len, lines=TT.lines, size=sizeof(toybuf); |
| |
| if ((toys.optc > 1 && !(toys.optflags & FLAG_q)) || toys.optflags & FLAG_v) { |
| // 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_raw(name); |
| if (len<1) break; |
| |
| for(i=0; i<len;) if (toybuf[i++] == '\n' && !--lines) break; |
| |
| xwrite(1, toybuf, i); |
| } |
| |
| TT.file_no++; |
| } |
| |
| void head_main(void) |
| { |
| char *arg = *toys.optargs; |
| |
| // handle old "-42" style arguments |
| if (arg && *arg == '-' && arg[1]) { |
| TT.lines = atolx(arg+1); |
| toys.optc--; |
| } else arg = 0; |
| loopfiles(toys.optargs+!!arg, do_head); |
| } |