2 isatty - returns 1 if fd assocatied with a tty
13 This function returns 1 if fd is associated with a tty, 0 otherwise.
17 > print isatty(files(0)), isatty(files(1)), isatty(files(2))
19 > fd = fopen("/dev/null", "r")
30 errno, fclose, feof, ferror, fflush, fgetc, fgetline, fgets, files, fopen,
31 fprintf, fputc, fputs, fseek, fsize, ftell, isfile, printf, prompt,
32 isassoc, isblk, isconfig, isdefined, iserror, iseven, isfile,
33 ishash, isident, isint, islist, ismat, ismult, isnull, isnum, isobj,
34 isobjtype, isodd, isprime, isrand, israndom, isreal, isrel,
35 issimple, issq, isstr, istype