4 Jan
2017
4 Jan
'17
2:54 a.m.
Peter Salus writes "The other innovation present in the Third Edition
was the pipe" ("A Quarter Century of Unix", p. 50). Yet, in the
corresponding sys/ken/sysent.c, the pipe system call seems to be a stump.
1, &fpe, /* 40 = fpe */
0, &dup, /* 41 = dup */
0, &nosys, /* 42 = pipe */
1, ×, /* 43 = times */
On the other hand, the Fourth Edition manual documents the pipe system
call, the construction of pipelines through the shell, and the use of wc
as a filter (without an input file, as was required in the Second Edition).
Would it therefore be correct to say that pipes were introduced in the
Fourth rather than the Third Edition?