On 1/28/21 2:16 AM, Anthony wrote:
> auto p = pipeProcess("ls");
> auto q = pipeProcess("cat", stdin = p.stdout); //it would be good to do
That would work if `cat` received the *contents* of the files (and with
a "-" command line switch). Since `ls` produces file names, you would
have to make the complete `cat` command line from `ls`'s output.
> Do I need to manually extract the output from pipes.stdin.readln
Seems to be so for the `ls | cat` case. But the following `find | grep`
example shows how two ends of pipes can be connected:
import std.stdio;
import std.process;
import std.range;
// BONUS: Enable one of the following lines to enjoy an issue.
// version = bonus_bug;
// version = bonus_bug_but_this_works;
void main() {
// Writes to 'a':
auto a = pipe();
auto lsPid = spawnProcess([ "find", "."], stdin, a.writeEnd);
scope (exit) wait(lsPid);
// Reads from 'a', writes to 'b':
auto b = pipe();
auto catPid = spawnProcess([ "grep", "-e", `\.d$` ], a.readEnd,
b.writeEnd);
scope (exit) wait(catPid);
version (bonus_bug) {
// Fails with the following error.
//
// "/usr/include/dmd/phobos/std/typecons.d(6540): Error:
// `"Attempted to access an uninitialized payload."`"
writefln!"Some of the D source files under the current
directory:\n%-( %s\n%)"(
b.readEnd.byLine);
} else version (bonus_bug_but_this_works) {
// Note .take at the end:
writefln!"Some of the D source files under the current
directory:\n%-( %s\n%)"(
b.readEnd.byLine.take(1000));
} else {
// The results are read from 'b':
writeln(b.readEnd.byLine);
}
}
I've discovered a strange issue, which can be observed by uncommenting
the 'version = bonus_bug;' line above. But comment that one back in and
uncomment the next line, now it works. (?)
Ali
