set $ENV{SHELL} if it's missing

[maxhq]

In the rare case when $ENV{SHELL} is not set, perlbrew currently prints out:

/opt/perlbrew/etc/bashrc: line 43: setenv: command not found.
Use of uninitialized value in pattern match (m//) at /loader/0x23ff038/App/perlbrew.pm line 34.

This patch assumes that the parent process is a shell and sets $ENV{SHELL} to the path of it's executable.

[coveralls]

Coverage decreased (-0.03%) when pulling f6765ea on maxhq:develop into c4782cf on gugod:develop.

[gugod]

Hi @maxhq,

The commit f6765ea only works on Linux where /proc is around... It'd be better to make it not broken on Mac and FreeBSD as well.

Also, SHELL is a dependency when interacting with perlbrew via its shell integration, perlbrew itself should be usable as a command. Do you have a init.d script that can demonstrate the error message ?

[maxhq]

Hi gugod,

that's my point: perlbrew should also work without $SHELL being set.

E.g. under Debian if you restart a service with service ... restart it will have a very reduced environment without $SHELL. If this service now starts perlbrew the mentioned error occurs.
Excerpt of /usr/sbin/service on a Debian 6.0.7:
exec env -i LANG="$LANG" PATH="$PATH" TERM="$TERM" "$SERVICEDIR/$SERVICE" ${ACTION} ${OPTIONS}

What about this modification of the patch:
$ENV{SHELL} ||= readlink joinpath("/proc", getppid, "exe") if -d "/proc";

I think the best would be if perlbrew did not use $SHELL at all...

[gugod]

@maxhq,

Interesting. Would you mind providing some skeleton of your service script that uses perlbrew ?

The dependency of $SHELL is mainly because of the constrained nature of shell scripting -- to implement use, switch, we inspect $SHELL, then print a dozen of shell script and expect the caller to eval() them. This can be completed rewritten so that the value of $SHELL is passed as a command line parameter.

OTOH, I'd imagine that the service script only need to "read" perlbrew env to bootstrap $PATH or $PERL5LIB -- in those cases, $SHELL should not be required.

[gugod]

I'll add the if -d "/proc"; check . But we should maybe work on removing the dependency of $SHEL variable.