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#include "gbos.h"
/* cut -f N [-d C] [file]: print field N of each line.
*
* The delimiter defaults to TAB, like cut(1); -d takes the first character of
* its argument, so `-d :` works - and since the shell has no quoting, `-d \\s`
* is how you say space (\\t tab, \\n newline). A line with no delimiter is passed through
* whole (what GNU cut does without -s), which is usually what you want when
* filtering mixed output on a 40-column screen. */
#define MAXLINE 80
/* The shell has no quoting, so a space or a tab cannot be typed as an
argument: "-d ' '" arrives as three tokens. Escapes are how you name them
here - \s space, \t tab, \n newline, \\ backslash. */
static char unesc1(const char *s, unsigned char *used) {
*used = 1;
if (s[0] != '\\' || !s[1]) return s[0];
*used = 2;
switch (s[1]) {
case 's': return ' ';
case 't': return '\t';
case 'n': return '\n';
case 'r': return '\r';
default: return s[1];
}
}
void main(void) {
char *argv[8];
char line[MAXLINE];
unsigned char argc = argv_parse(argv, 8);
char *fv = optval(argv, argc, 'f');
char *dv = optval(argv, argc, 'd');
unsigned char dused;
char delim = dv ? unesc1(dv, &dused) : '\t';
unsigned char want = fv ? atou(fv) : 1;
unsigned char len = 0, fd = NOFD, i, field, start, end;
char *fname = 0;
int ch;
if (want == 0) want = 1;
for (i = 0; i < argc; i++) {
if (argv[i][0] == '-') continue;
if (fv == argv[i] || dv == argv[i]) continue;
fname = argv[i];
break;
}
if (fname) {
fd = open(fname, O_READ);
if (fd == EISDIR) {
puts("cut: is a directory");
nl();
sexit(2);
}
if (fd == NOFD) {
puts("cut: no such file");
nl();
sexit(2);
}
}
for (;;) {
if (fd == NOFD) {
char c = readc();
ch = (c == EOF) ? -1 : c;
} else ch = fgetc(fd);
if (ch == '\r') continue;
if (ch >= 0 && ch != '\n') {
if (len < MAXLINE) line[len++] = (char)ch;
continue;
}
if (ch < 0 && len == 0) break;
/* walk to the wanted field */
field = 1;
start = 0;
for (i = 0; i <= len; i++) {
if (i == len || line[i] == delim) {
if (field == want) break;
field++;
start = (unsigned char)(i + 1);
}
}
end = i;
if (field == want && start <= len) writes(line + start, (unsigned char)(end - start));
nl();
len = 0;
if (ch < 0) break;
}
if (fd != NOFD) close(fd);
}
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