diff options
Diffstat (limited to '')
| -rw-r--r-- | c/head.c | 27 |
1 files changed, 19 insertions, 8 deletions
@@ -1,17 +1,28 @@ #include "gbos.h" -/* head [-n N] [N]: print the first N lines of stdin (default 10). */ +/* head [-n N] [N] [file]: first N lines of a file or stdin (default 10). */ void main(void) { char *argv[8]; unsigned char argc = argv_parse(argv, 8); char *nv = optval(argv, argc, 'n'); - unsigned char n = 10, lines = 0; - char c; + unsigned char n = 10, lines = 0, i, fd = NOFD; + char *fname = 0; + int ch; if (nv) n = atou(nv); - else if (argc > 0 && argv[0][0] >= '0' && argv[0][0] <= '9') n = atou(argv[0]); + for (i = 0; i < argc; i++) { + if (argv[i][0] == '-') continue; + if (nv == argv[i]) continue; + if (!nv && argv[i][0] >= '0' && argv[i][0] <= '9') { n = atou(argv[i]); continue; } + fname = argv[i]; break; + } + if (fname) { + fd = open(fname, O_READ); + if (fd == NOFD) { puts("head: no such file"); nl(); return; } + } for (;;) { - c = readc(); - if (c == EOF) break; - if (lines < n) putc(c); - if (c == '\n') lines++; + if (fd == NOFD) { char c = readc(); if (c == EOF) break; ch = c; } + else { ch = fgetc(fd); if (ch < 0) break; } + if (lines < n) putc((char)ch); + if (ch == '\n') lines++; } + if (fd != NOFD) close(fd); } |