On Mon, Nov 16, 2020 at 08:11:04PM +0900, Tetsuo Handa wrote: > Hello. > > Below is a loadable kernel module which attempts to read (for example) /proc/interrupts from > kernel using usermode driver interface. What is strange is that the total bytes obtained by > doing "wc -c /proc/interrupts" from userspace's shell and trying to insmod this kernel module > differs; for unknown reason, kernel_read() returns "#!/bin/cat /proc/interrupts\n" (28 bytes) > at the end of input. Because /bin/cat writes it out ;-) $ echo "#!/bin/echo foo" >/tmp/a $ chmod +x /tmp/a $ /tmp/a foo /tmp/a $ IOW, same way #!/bin/sh -e in the beginning of /tmp/foo.sh results in exec of /bin/sh with -e and /tmp/foo.sh in the arguments, #!/bin/cat /proc/interrupts in /tmp/bar.sh will result in exec of /bin/cat with /proc/interrupts and /tmp/bar.sh in parameters. With cat(1) doing what it's supposed to do.
