Re: extension of file-test primitives?

[dethrophes]

Well technically I don't *have* to accept the performance penalty.

As I can just use the posix comform syntax, which is quicker.

And just becasue I was curious as to how much quicker it is. Now 
admittedly it's not the biggest difference in perf, but I don't see any 
real point in using a slower one.

    test_file_1(){
        test -f "${1:?Missing Test File}" -a -x "${1}"
    }

    test_file_2(){
        test -f "${1:?Missing Test File}" && test -x "${1}"
    }

    test_case(){
        local cnt=${1:?Missing repeat count}
        local test_func=${2:?Missing Test Function}
        local test_file=${3:?Missing Test File}

        echo "${test_func}" "${test_file}"
        while [ $(((cnt -= 1 ) )) != 0 ]; do
      "${test_func}" "${test_file}"
        done
    }
    : ${TMPDIR:=/tmp}
    setup_test(){
        touch "${TMPDIR}/file"
        touch "${TMPDIR}/exec_file"
        chmod a+x "${TMPDIR}/exec_file"
        time test_case 10000 test_file_1 "${TMPDIR}/file"
        time test_case 10000 test_file_2 "${TMPDIR}/file"
        time test_case 10000 test_file_1 "${TMPDIR}/exec_file"
        time test_case 10000 test_file_2 "${TMPDIR}/exec_file"
    }

~/ks_qnx/test_bash.sh setup_test
test_file_1 /tmp/file

real    0m0.132s
user    0m0.128s
sys     0m0.004s
test_file_2 /tmp/file

real    0m0.148s
user    0m0.116s
sys     0m0.028s
test_file_1 /tmp/exec_file

real    0m0.138s
user    0m0.128s
sys     0m0.008s
test_file_2 /tmp/exec_file

real    0m0.153s
user    0m0.128s
sys     0m0.024s


Am 23.08.2017 um 16:27 schrieb Chet Ramey:
> On 8/23/17 10:24 AM, Dethrophes wrote:
> > > > Which I always understood as the correct way of doing this in the
> > > first place...
> > >
> > > It's not as good as multiple test commands: test -f file && test -x
> > > file.
> > > There's no ambiguity and you get short-circuiting.
> > Only if you are using the test built-in, otherwise the latter means 2 
> > spawns/forks however the shell in question calls the test exec.
> Since bash has a test builtin, this isn't exactly on point. But you have
> to accept this kind of micro-inefficiency with a shell that sacrifices
> speed for size.