• seany (7/7) Jun 08 2021 I have compiled a complex project via `dub build`.
• Steven Schveighoffer (10/22) Jun 08 2021 Are you expecting input as well as sending output?
• seany (13/37) Jun 08 2021 Hi
• Steven Schveighoffer (6/21) Jun 08 2021 Yes, that is exactly the case. `tee` and `tail` commands are not
• seany (3/25) Jun 08 2021 Ok, thank you. it works.

seany <seany uni-bonn.de> writes:

I have compiled a complex project via `dub build`.

I used both `-b release` and `-b debug`.

But i cant redirect the output (generated by `writeln`) to a file.

I call by : `./executable --param p1 > a`. But execution hangs 
immediately. If I do `./executable --param p1 ` no issue.

What am I doing wrong?

thank you.

Steven Schveighoffer <schveiguy gmail.com> writes:

On 6/8/21 8:38 AM, seany wrote:
 I have compiled a complex project via `dub build`.
 
 I used both `-b release` and `-b debug`.
 
 But i cant redirect the output (generated by `writeln`) to a file.
 
 I call by : `./executable --param p1 > a`. But execution hangs 
 immediately. If I do `./executable --param p1 ` no issue.
 
 What am I doing wrong?
 
 thank you.

Are you expecting input as well as sending output?

A common behavior difference between console streams and file streams 
(including in D) is that when the library detects it's sending to a 
console, it flushes buffered output after every newline. When it's 
sending to a file (or other stream type), it only sends output when the 
buffer is full (usually about 4k bytes).

The hang sounds like it has buffered up its output ready to send, and 
then is waiting for input to continue.

-Steve

seany <seany uni-bonn.de> writes:

On Tuesday, 8 June 2021 at 13:51:10 UTC, Steven Schveighoffer 
wrote:
 On 6/8/21 8:38 AM, seany wrote:
 I have compiled a complex project via `dub build`.
 
 I used both `-b release` and `-b debug`.
 
 But i cant redirect the output (generated by `writeln`) to a 
 file.
 
 I call by : `./executable --param p1 > a`. But execution hangs 
 immediately. If I do `./executable --param p1 ` no issue.
 
 What am I doing wrong?
 
 thank you.

 Are you expecting input as well as sending output?

 A common behavior difference between console streams and file 
 streams (including in D) is that when the library detects it's 
 sending to a console, it flushes buffered output after every 
 newline. When it's sending to a file (or other stream type), it 
 only sends output when the buffer is full (usually about 4k 
 bytes).

 The hang sounds like it has buffered up its output ready to 
 send, and then is waiting for input to continue.

 -Steve

Hi

Thank you for pointing this out.

Indeed, much later in the code, there is a `readln()`.
But, the program needs to run 1-2 minutes, until it reaches that 
point - it is doing a complex AI calculation.

However, for these 1-2 minutes, there is no output. Not via 
`tee`command, also not when i do a `tail -f a` (`a` is the 
logfile as in my last mail). I expect  the output of these 1-2 
minutes, until the `readln` point to be visible via either of 
these to methods.

Is it still the same case as you describe?

Steven Schveighoffer <schveiguy gmail.com> writes:

On 6/8/21 10:05 AM, seany wrote:
 
 Hi
 
 Thank you for pointing this out.
 
 Indeed, much later in the code, there is a `readln()`.
 But, the program needs to run 1-2 minutes, until it reaches that point - 
 it is doing a complex AI calculation.
 
 However, for these 1-2 minutes, there is no output. Not via 
 `tee`command, also not when i do a `tail -f a` (`a` is the logfile as in 
 my last mail). I expect  the output of these 1-2 minutes, until the 
 `readln` point to be visible via either of these to methods.
 
 Is it still the same case as you describe?

Yes, that is exactly the case. `tee` and `tail` commands are not 
considered a console.

Insert a `stdout.flush;` every time you want more output to appear, and 
it should fix the issue.

-Steve

seany <seany uni-bonn.de> writes:

On Tuesday, 8 June 2021 at 14:15:47 UTC, Steven Schveighoffer 
wrote:
 On 6/8/21 10:05 AM, seany wrote:
 
 Hi
 
 Thank you for pointing this out.
 
 Indeed, much later in the code, there is a `readln()`.
 But, the program needs to run 1-2 minutes, until it reaches 
 that point - it is doing a complex AI calculation.
 
 However, for these 1-2 minutes, there is no output. Not via 
 `tee`command, also not when i do a `tail -f a` (`a` is the 
 logfile as in my last mail). I expect  the output of these 1-2 
 minutes, until the `readln` point to be visible via either of 
 these to methods.
 
 Is it still the same case as you describe?

 Yes, that is exactly the case. `tee` and `tail` commands are 
 not considered a console.

 Insert a `stdout.flush;` every time you want more output to 
 appear, and it should fix the issue.

 -Steve

Ok, thank you. it works.