Re: A bug when using bash shell variable

[Alex fxmbsw7 Ratchev]

args=( -append "opt with spaces" )
cmd "${args[@]}" other_arg

On Thu, Jan 13, 2022, 11:33 ju nan <kfggww@outlook.com> wrote:

> I hava run into some troubles when I use bash shell to execute qemu, here
> is the log.
>
>
>
>   1.  Run qemu with arguments directly in bash shell, I use strace to
> track execve syscall, everything goes well
>
> junan@u0:~/Documents/coding/run-riscv-qemu-linux$ strace
> qemu-system-riscv64 -nographic -machine virt -kernel
> ../linux-5.11/arch/riscv/boot/Image -append "root=/dev/vda ro
> console=ttyS0" -drive file=root.ext4,format=raw,id=hd0 -device
> virtio-blk-device,drive=hd0
> execve("/usr/bin/qemu-system-riscv64", ["qemu-system-riscv64",
> "-nographic", "-machine", "virt", "-kernel",
> "../linux-5.11/arch/riscv/boot/Im"..., "-append", "root=/dev/vda ro
> console=ttyS0", "-drive", "file=root.ext4,format=raw,id=hd0", "-device",
> "virtio-blk-device,drive=hd0"], 0x7ffc39cda858 /* 58 vars */) = 0
> brk(NULL)                               = 0x55bb77e20000
> arch_prctl(0x3001 /* ARCH_??? */, 0x7ffd61474450) = -1 EINVAL (Invalid
> argument)
> access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or
> directory)
> openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
>
>
>   1.  But when I use bash variables to do it again, something wired
> happend, as you can see, the argument "root=/dev/vda ro console=ttyS0" is
> splited into different parts, so qemu did not start successfully 😋
>
>
> junan@u0:~/Documents/coding/run-riscv-qemu-linux$ echo $QEMU
> qemu-system-riscv64
> junan@u0:~/Documents/coding/run-riscv-qemu-linux$ echo $QOPTIONS
> -nographic -machine virt -kernel ../linux-5.11/arch/riscv/boot/Image
> -append "root=/dev/vda ro console=ttyS0" -drive
> file=root.ext4,format=raw,id=hd0 -device virtio-blk-device,drive=hd0
>
> junan@u0:~/Documents/coding/run-riscv-qemu-linux$ strace $QEMU $QOPTIONS
> execve("/usr/bin/qemu-system-riscv64", ["qemu-system-riscv64",
> "-nographic", "-machine", "virt", "-kernel",
> "../linux-5.11/arch/riscv/boot/Im"..., "-append", "\"root=/dev/vda", "ro",
> "console=ttyS0\"", "-drive", "file=root.ext4,format=raw,id=hd0", "-device",
> "virtio-blk-device,drive=hd0"], 0x7ffe1e71a928 /* 58 vars */) = 0
> brk(NULL)                               = 0x5613dfdc4000
>
>
> Thank you all for making so many excellent softwares, and I wish this will
> help to improve the bash shell 😊.
>