Re: Fwd: Behavior change in Dash pipes/read?

Hi,

already tried that but it didn't work. I'm guessing strace-macos
doesn't pass stdin to the spawned process.
Figured I could try attach-to-process approach, are these of any help?

> cat test.sh
echo $$
sleep 10
read -r x
echo "$x"

> echo hello | /nix/store/4kjsgkcxqfadycyspzfrf9gg5n5bpc27-dash-0.5.12/bin/=
dash ./test.sh
8914
> strace -p 8914
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
read(0, "h", 1) =3D 1
read(0, "e", 1) =3D 1
read(0, "l", 1) =3D 1
read(0, "l", 1) =3D 1
read(0, "o", 1) =3D 1
read(0, "\n", 1) =3D 1
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
write(1, "hello\n", 6) =3D 6
read(10, "echo $$\nsleep 10\nread -r x\necho ...", 1024) =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0

echo hello | /nix/store/kra243nir1p3pyc50312w3nmirbcbxr0-dash-0.5.13.1/bin/=
dash
./test.sh
8931
> strace -p 8931
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
ioctl(0, TIOCGETA, 0x100498498) =3D -1 EPERM (Operation not permitted)
lseek(0, 0, SEEK_CUR) =3D -1 EPERM (Operation not permitted)
pipe() =3D 0
fcntl(3, F_DUPFD_CLOEXEC, 10) =3D 11
close(3) =3D 0
fcntl(4, F_DUPFD_CLOEXEC, 10) =3D 12
close(4) =3D 0
read(0, "h", 1) =3D 1
read(0, "e", 1) =3D 1
read(0, "l", 1) =3D 1
read(0, "l", 1) =3D 1
read(0, "o", 1) =3D 1
read(0, "\n", 1) =3D 1
read(0, "\n", 1) =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
write(1, "\n", 1) =3D 1
read(10, "\nread -r x\necho \"$x\"\n\0\0\0\0\0\0\0\0\0\0\0...", 1024) =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0
sigprocmask(SIG_BLOCK, 0x0, "[]") =3D 0

--- Jyri-Matti L=C3=A4hteenm=C3=A4ki

ke 4.2.2026 klo 11.16 Herbert Xu ([email protected]) kirjoitti:
>
> Jyri-Matti L=C3=A4hteenm=C3=A4ki <[email protected]> wrote:
> >
> > The results are as attachments. But
> > https://github.com/Mic92/strace-macos says it doesn't follow forks, so
> > I guess the interesting parts are missing?
> > Running /nix/store/wy9ass74g4yc1x354ydbdlxkfkxxjv2x-dash-0.5.13.1/bin/d=
ash
> > -c 'echo hello > hello; { read -r x; echo "$x"; } < hello' seems to
> > work correctly.
>
> OK try running strace inside the script:
>
> echo hello | strace /path/to/dash -c 'read -r x; echo "$x"'
>
> Thanks,
> --
> Email: Herbert Xu <[email protected]>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt