Inconsistent behavior

[0x7FFFFFFFFFFFFFFF]

I'm using version 1.2.2 and I have the following program.

fn main() -> eyre::Result<()> {
std::env::set_current_dir(r##"f:\temp"##);
let output = cmd_lib::spawn_with_output!(ls -la)?.wait_fun_result()?;
println!("{:?}", output);
Ok(())
}

When I run it, I can get the expected result like:

"total 5996106\ndrwxr-xr-x 1 admin None 0 Sep 25 16:26 .\n..............................."

When I change the command ls -la to more complex one (which probably takes several seconds to complete), I get empty output.

fn main() -> eyre::Result<()> {
std::env::set_current_dir(r##"f:\temp"##);
let output = cmd_lib::spawn_with_output!(
ffmpeg -i 1.mp4 -i a2.png -y -filter_complex "overlay=x=263:y=752" -c:a copy -max_muxing_queue_size 99999 -y test.mp4
)?.wait_fun_result()?;
println!("{:?}", output);
Ok(())
}

Output is:

""

But can I find the produced output file of the ffmpeg command, which indicates the command did run. If I enabled the logger like this:

use cmd_lib::init_builtin_logger;
fn main() -> eyre::Result<()> {
init_builtin_logger();
std::env::set_current_dir(r##"f:\temp"##);
let output = cmd_lib::spawn_with_output!(
ffmpeg -i 1.mp4 -i a2.png -ss 00:00:00 -to 00:01:00 -y -filter_complex "overlay=x=263:y=752" -c:a copy -max_muxing_queue_size 99999 -y testtttt.mp4
)?.wait_fun_result()?;
println!("{:?}", output);
Ok(())
}

I can get the ffmpeg output in the console:

INFO - ffmpeg version N-103679-g7bbad32d5a-20210918 Copyright (c) 2000-2021 the FFmpeg developers
INFO - built with gcc 10-win32 (GCC) 20210408
INFO - configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-
...
INFO - [libx264 @ 0000010cf15da6c0] ref B L1: 97.3% 2.7%
INFO - [libx264 @ 0000010cf15da6c0] kb/s:134.12
""

But note the "" at the end of the output, I still can't get the output in the variable output and it still contains an empty string.

Why for simple command, the output is captured in a variable. But for complex command, it doesn't do this. Is this inconsistence a bug? How can I store the command output in a variable when the command is kinda complex? Thank.

[tao-guo]

By default only stdout output is captured into variable, and stderr is logged into your logger. You can redirect stderr to stdout if you want to capture it into variable: let v = run_fun!(xxx 2>&1)?;. Also don't use spawn API if you are not doing things concurrently.

[0x7FFFFFFFFFFFFFFF]

Thanks for the suggestion. I changed the command to this:

let output = cmd_lib::spawn_with_output!(
ffmpeg -i 1.mp4 -i a2.png -ss 00:00:00 -to 10 -y -filter_complex "overlay=x=263:y=752" -c:a copy -max_muxing_queue_size 99999 -y testtttt.mp4 2>result.txt
)?.wait_fun_result()?;

Since ffmpeg always log to stderr, and I redirected stderr to result.txt, I can get the log in the text file and the output variable is empty. However, when I change the command to this:

let output = cmd_lib::spawn_with_output!(
ffmpeg -i 1.mp4 -i a2.png -ss 00:00:00 -to 10 -y -filter_complex "overlay=x=263:y=752" -c:a copy -max_muxing_queue_size 99999 -y testtttt.mp4 2>&1
)?.wait_fun_result()?;

Here I redirect stderr to stdout, which should make the variable output capture both stdout and stderr. However, the behavior is that the whole output get's logged in the terminal and the variable output is still empty. Where am I wrong?

[rust-shell-script]

Try let output = run_fun!(ffmgeg ... |& cat)? to see if it works. The Stdio::piped() API has some known issues for redirection, and it will be replaced in the future when I have enough time to fix it.

[0x7FFFFFFFFFFFFFFF]

Try let output = run_fun!(ffmgeg ... |& cat)? to see if it works. The Stdio::piped() API has some known issues for redirection, and it will be replaced in the future when I have enough time to fix it.

Yes, this works! Thanks for the trick. Do you want me to open an issue to track the redirection improvement you mentioned?