digitalmars.D.learn - interacting with a process with redirected stdin/stdout/stderr
- Timothee Cour (23/23) Jul 14 2013 I'm trying to interact with a process using std.process and
- timotheecour (25/51) Jul 14 2013 I tried using a separate thread for reading the process' stdout.
- Anthony Goins (5/60) Jul 16 2013 Are you looking for select() or poll()
- Timothee Cour (7/75) Jul 16 2013 Thanks, I had actually used select to solve another problem I had:
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
----
auto pipes=pipeShell("myprocess",Redirect.all);
while(true){
pipes.stdin.rawWrite(some_command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
----
This doesn't work because it might block inside pipes.stdout.byLine, as the
process is requesting more inputs to be written to its stdin before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked thread when we no
longer need it?
Any detailed example would help.
Thanks!
Jul 14 2013
On Monday, 15 July 2013 at 03:49:10 UTC, Timothee Cour wrote:
I'm trying to interact with a process using std.process and
redirected stdin/stdout/stderr.
What would be the recommended way?
For example:
----
auto pipes=pipeShell("myprocess",Redirect.all);
while(true){
pipes.stdin.rawWrite(some_command);
foreach (line; pipes.stdout.byLine) {
//do something with line
}
}
----
This doesn't work because it might block inside
pipes.stdout.byLine, as the
process is requesting more inputs to be written to its stdin
before
outputting more bytes to its stdout.
What's the right approach?
* fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work
* reading pipes.stdout inside a separate thread?
In that second case, how to cleanly dispose of a blocked thread
when we no
longer need it?
Any detailed example would help.
Thanks!
I tried using a separate thread for reading the process' stdout.
It works, except that sometimes the output is shuffled out of
order.
Is there anything buggy in this:
----
__gshared string output;
void readBlocking(){
while ((c = fgetc(filepointer)) >= 0)
output~=cast(char) c;
//NOTE: i can use something more efficient here but that's beside
the question
}
thread = new Thread(& readBlocking);
output=null;
while(true){
Thread.sleep(...);
if(condition) break;
}
//now output is shuffled out of order sometimes
----
Furthermore, is there a standard way to tell when a process is
waiting for stdin input ? (cf condition above). Currently I'm
checking whether 'output' was modified within a timeout period T,
but that's fragile and incurs of penalty of T at least.
Jul 14 2013
On Monday, 15 July 2013 at 06:46:52 UTC, timotheecour wrote:On Monday, 15 July 2013 at 03:49:10 UTC, Timothee Cour wrote:Are you looking for select() or poll() Poll I believe is posix only but I think select is more widely available. Not much of an answer but I hope it helpsI'm trying to interact with a process using std.process and redirected stdin/stdout/stderr. What would be the recommended way? For example: ---- auto pipes=pipeShell("myprocess",Redirect.all); while(true){ pipes.stdin.rawWrite(some_command); foreach (line; pipes.stdout.byLine) { //do something with line } } ---- This doesn't work because it might block inside pipes.stdout.byLine, as the process is requesting more inputs to be written to its stdin before outputting more bytes to its stdout. What's the right approach? * fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work * reading pipes.stdout inside a separate thread? In that second case, how to cleanly dispose of a blocked thread when we no longer need it? Any detailed example would help. Thanks!I tried using a separate thread for reading the process' stdout. It works, except that sometimes the output is shuffled out of order. Is there anything buggy in this: ---- __gshared string output; void readBlocking(){ while ((c = fgetc(filepointer)) >= 0) output~=cast(char) c; //NOTE: i can use something more efficient here but that's beside the question } thread = new Thread(& readBlocking); output=null; while(true){ Thread.sleep(...); if(condition) break; } //now output is shuffled out of order sometimes ---- Furthermore, is there a standard way to tell when a process is waiting for stdin input ? (cf condition above). Currently I'm checking whether 'output' was modified within a timeout period T, but that's fragile and incurs of penalty of T at least.
Jul 16 2013
Timothee Cour <thelastmammoth gmail.com> On Tue, Jul 16, 2013 at 10:01 AM, Anthony Goins <neontotem gmail.com> wrote:On Monday, 15 July 2013 at 06:46:52 UTC, timotheecour wrote:Thanks, I had actually used select to solve another problem I had: [std.process: how to process stdout chunk by chunk without waiting for process termination] That should work for here as well. I think std.process is a bit limited currently, I keep having to implement basic stuff it doesn't support.On Monday, 15 July 2013 at 03:49:10 UTC, Timothee Cour wrote:Are you looking for select() or poll() Poll I believe is posix only but I think select is more widely available. Not much of an answer but I hope it helpsI'm trying to interact with a process using std.process and redirected stdin/stdout/stderr. What would be the recommended way? For example: ---- auto pipes=pipeShell("myprocess",**Redirect.all); while(true){ pipes.stdin.rawWrite(some_**command); foreach (line; pipes.stdout.byLine) { //do something with line } } ---- This doesn't work because it might block inside pipes.stdout.byLine, as the process is requesting more inputs to be written to its stdin before outputting more bytes to its stdout. What's the right approach? * fcntl(fd, F_SETFL, O_NONBLOCK); didn't seem to work * reading pipes.stdout inside a separate thread? In that second case, how to cleanly dispose of a blocked thread when we no longer need it? Any detailed example would help. Thanks!I tried using a separate thread for reading the process' stdout. It works, except that sometimes the output is shuffled out of order. Is there anything buggy in this: ---- __gshared string output; void readBlocking(){ while ((c = fgetc(filepointer)) >= 0) output~=cast(char) c; //NOTE: i can use something more efficient here but that's beside the question } thread = new Thread(& readBlocking); output=null; while(true){ Thread.sleep(...); if(condition) break; } //now output is shuffled out of order sometimes ---- Furthermore, is there a standard way to tell when a process is waiting for stdin input ? (cf condition above). Currently I'm checking whether 'output' was modified within a timeout period T, but that's fragile and incurs of penalty of T at least.
Jul 16 2013