On 07/14/2017 03:13 PM, Greg Wooledge wrote: > On Sat, Jul 15, 2017 at 02:59:41AM +0700, Robert Elz wrote: >> IMO, if SHELL gets unset (it is usually initialised by login, or its >> equivalent), it should simply stay unset, and not be set to anything, >> until some user (or script) decides to set it again. > > wooledg:~$ unset SHELL > wooledg:~$ bash -c 'echo "$SHELL"' > /bin/bash > wooledg:~$ ksh -c 'echo "$SHELL"' > /bin/sh > wooledg:~$ zsh -c 'echo "$SHELL"' > > wooledg:~$ tcsh -c 'echo "$SHELL"' > SHELL: Undefined variable. > > Looks like there's not much agreement here. >
Good thing is bash doesn't export SHELL if it wasn't already exported, and most shells seem to preserve the value of SHELL exported by some parent. I see mksh sets -x if SHELL was previously unset... I suppose that might cause a problem in some scenario (but probably not).
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