Shell invocation results in a segfault on OpenBSD

[vaygr]

When shell invocation (!) is performed, nnn crashes while spawning and gets back to its primary UI.

[vaygr]

More debugging info:

Starting program: /home/user/nnn-1.5/nnn 
[New process 99364]

Program received signal SIGSEGV, Segmentation fault.
[Switching to thread 565247]
*_libc_strtol (nptr=0x0, endptr=0x0, base=10) at /usr/src/lib/libc/stdlib/strtol.c:68
68      /usr/src/lib/libc/stdlib/strtol.c: No such file or directory.
        in /usr/src/lib/libc/stdlib/strtol.c
(gdb) bt
#0  *_libc_strtol (nptr=0x0, endptr=0x0, base=10) at /usr/src/lib/libc/stdlib/strtol.c:68
#1  0x000002656d897530 in *_libc_atoi (str=Variable "str" is not available.
) at /usr/src/lib/libc/stdlib/atoi.c:36
#2  0x0000026307a013a0 in spawn (file=0x7f7ffffd0d0f "/bin/ksh", arg1=0x0, arg2=0x0, dir=0x26307c0fde0 "/home/user/nnn-1.5", flag=129 '\201') at nnn.c:571
#3  0x0000026307a072d9 in browse (ipath=0x26307c101e0 "/home/user/nnn-1.5", ifilter=0x26307b0a6fc "^[^.]") at nnn.c:2775
#4  0x0000026307a078c0 in main (argc=1, argv=0x7f7ffffd0a78) at nnn.c:2937

[vaygr]

I guess the answer is $SHLVL is not supported by ksh. It is supported by bash, mksh and fish
however -- I checked those. But since it's only an info message, maybe it can be optional.

[jarun]

First, thanks a lot for testing nnn out and for the issues and PRs! I will review and pull them in a few hours.

Regarding the issue:

It can be optional but it's quite helpful. So I'm thinking how about checking the shell and if it's bash, fish or mksh show this msg? is there any alternative on ksh?

[jarun]

Resolved at d835f72.

[vaygr]

Well, let's pave a bright future for nnn :) there are many shells right now, and there will probably more in 2052, all w/ or w/o support with this special variable.

So I think it's cleaner to rely on this variable existence and use it if it's there rather than add/remove support shells based on their names every time 1) new shell with a new name is developed; 2) support for this variable is added/removed. So we'd actually need to track it or rely on users' reports.

On the other hand, there we just check the var and use it if it's available -- cheap and simple.

[jarun]

Makes sense, the reason I already accepted the PR. ;)