For some time I have been meaning to check out mksh, and your email
prompted me to install it. The first thing I noticed was how good the
documentation is (the bash man page is missing a lot of stuff).
I played around with mksh for a while and noticed some other differences
with bash. Parameter assignment using here-docs is a nice feature. Another
difference is double logical complement. The mksh result was the one I was
expecting --
mksh:
$ ! ! perl -e 'exit 2' ; echo $?
1
$ ! ( ! perl -e 'exit 2' ) ; echo $?
1
$ ! { ! perl -e 'exit 2' ; } ; echo $?
1
bash:
$ ! ! perl -e 'exit 2' ; echo $?
2
$ ! ( ! perl -e 'exit 2' ) ; echo $?
1
$ ! { ! perl -e 'exit 2' ; } ; echo $?
1
Another difference is parameter assignment --
mksh:
$ a=x
$ a=blah :
$ echo $a
blah
$ a=foo exec </dev/stdin
$ echo $a
foo
bash:
$ a=x
$ a=blah :
$ echo $a
x
$ a=foo exec </dev/stdin
$ echo $a
x
The mksh man page says, "the assignments are in effect only for the
duration of the command". In bash you might do,
$ a=blah $cmd
and get different results; given cmd="" the assignment sticks, but given
cmd=":" the assignment is a NOP. Could be useful perhaps.
On the other hand...
mksh:
$ cmd=
$ exec $cmd
$ cmd=:
$ exec $cmd
[terminates]
bash:
$ cmd=
$ exec $cmd
$ cmd=:
$ exec $cmd
-bash: exec: :: not found
$
So is ":" a NOP, or is it a builtin command? Beats me!
Anyway, I'm picking nits. Here's where the rubber hits the road:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12457 fthain 20 0 3524 1872 1572 S 0.0 0.1 0:00.01 bash
12734 fthain 20 0 2228 712 608 S 0.0 0.0 0:00.00 mksh
$ ls -l /bin/mksh /bin/bash
-rwxr-xr-x 1 root root 263860 Mar 29 12:51 /bin/mksh
-rwxr-xr-x 1 root root 720796 Sep 3 2012 /bin/bash
So thanks for the excellent work!
Finn
P.S. For the sake of completeness:
$ /bin/mksh -c echo\ \$KSH_VERSION
@(#)MIRBSD KSH R44 2013/02/24
$ /bin/bash -c echo\ \$BASH_VERSION
4.2.37(1)-release
P.P.S. I'm not subscribed so please Cc replies.
