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digitalmars.D.learn - How do I get the output of the time bash command?

reply Anthony <anthoq88 gmail.com> writes:
I'm trying to read the timed output of a pipeShell command but it 
only results in empty output.

Does anyone know why this is?


```
     auto p = pipeShell("time ls");

     foreach(str; p.stdout.byLine) {
         writefln("%s",str);
     }
```
Jan 27 2021
next sibling parent reply Arafel <er.krali gmail.com> writes:
On 27/1/21 10:35, Anthony wrote:

 
 I'm trying to read the timed output of a pipeShell command but it only 
 results in empty output.
 
 Does anyone know why this is?
 
 
 ```
      auto p = pipeShell("time ls");
 
      foreach(str; p.stdout.byLine) {
          writefln("%s",str);
      }
 ```


I'm not sure why you get an empty output, you should get at least the 
`ls` output unless it's an empty directory (or one with only "dot" files).

However, in any case `time` returns the timing information through 
`stderr`, not `stdout`[1]. You can try [2,3] (untested):

```
auto p = pipeShell("time ls", Redirect.stderrToStdout);
```

Best,

A.

[1]: https://linux.die.net/man/1/time
[2]: https://dlang.org/library/std/process/pipe_shell.html
[3]: https://dlang.org/library/std/process/redirect.html
Jan 27 2021
parent Anthony <anthoq88 gmail.com> writes:
On Wednesday, 27 January 2021 at 09:58:18 UTC, Arafel wrote:

 On 27/1/21 10:35, Anthony wrote:

 
 I'm trying to read the timed output of a pipeShell command but 
 it only results in empty output.
 
 Does anyone know why this is?
 
 
 ```
      auto p = pipeShell("time ls");
 
      foreach(str; p.stdout.byLine) {
          writefln("%s",str);
      }
 ```


 I'm not sure why you get an empty output, you should get at 
 least the `ls` output unless it's an empty directory (or one 
 with only "dot" files).

 However, in any case `time` returns the timing information 
 through `stderr`, not `stdout`[1]. You can try [2,3] (untested):

 ```
 auto p = pipeShell("time ls", Redirect.stderrToStdout);
 ```

 Best,

 A.

 [1]: https://linux.die.net/man/1/time
 [2]: https://dlang.org/library/std/process/pipe_shell.html
 [3]: https://dlang.org/library/std/process/redirect.html


Thanks! I think this was the issue.
Turns out that pipeShell uses sh not bash so the "time" program 
isn't available.
When I printed stderr, it showed me the error.
Jan 27 2021
prev sibling next sibling parent reply Marcone <marcone email.com> writes:
On Wednesday, 27 January 2021 at 09:35:21 UTC, Anthony wrote:

 I'm trying to read the timed output of a pipeShell command but 
 it only results in empty output.

 Does anyone know why this is?


 ```
     auto p = pipeShell("time ls");

     foreach(str; p.stdout.byLine) {
         writefln("%s",str);
     }
 ```


writeln(executeShell("time ls")[1]);
Jan 27 2021
parent bachmeier <no spam.net> writes:
On Wednesday, 27 January 2021 at 09:58:25 UTC, Marcone wrote:

 On Wednesday, 27 January 2021 at 09:35:21 UTC, Anthony wrote:

 I'm trying to read the timed output of a pipeShell command but 
 it only results in empty output.

 Does anyone know why this is?


 ```
     auto p = pipeShell("time ls");

     foreach(str; p.stdout.byLine) {
         writefln("%s",str);
     }
 ```


 writeln(executeShell("time ls")[1]);


This is the correct answer. The documentation for pipeShell says


 Like the functions they wrap, these functions return 
 immediately, leaving the child process to execute in parallel 
 with the invoking process. It is recommended to always call 
 wait on the returned ProcessPipes.pid, as detailed in the 
 documentation for wait.
Jan 27 2021
prev sibling parent Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= <aferust gmail.com> writes:
On Wednesday, 27 January 2021 at 09:35:21 UTC, Anthony wrote:

 I'm trying to read the timed output of a pipeShell command but 
 it only results in empty output.

 Does anyone know why this is?


 ```
     auto p = pipeShell("time ls");

     foreach(str; p.stdout.byLine) {
         writefln("%s",str);
     }
 ```


Probably, just getting a string output is not enough. It looks a 
little outdated, but there is this library:

https://code.dlang.org/packages/dexpect
Jan 27 2021