Added default tape defenition for compile-time and reading path to device from TAPE environment variable

[svalx]

Introduce default device feature. If -f option omitted, stenc will try to read TAPE environment variable and use it for device name definition. If TAPE not defined, the default device name will be used. The default device name is /dev/nst0 and can be changed at compile-time by using the --with-default-tape-drive configure option.

[jonasstein]

I guess that every user of stenc also uses mt which evaluates the TAPE environment variable too.
They write in the man page

-f, -t The path of the tape device on  which to operate.  
       If neither of those options is given, and the environment variable 
       TAPE is set, it is used.  Otherwise, a default device defined in
       the file /usr/include/sys/mtio.h is used (note that the actual path 
       to mtio.h can vary per architecture and/or distribution).

https://github.com/iustin/mt-st

[svalx]

In /usr/include/sys/mtio.h it looks like this:

/* Specify default tape device.  */
#ifndef DEFTAPE
# define DEFTAPE        "/dev/tape"
#endif

But modern distributions doesn't have /dev/tape as link to /dev/nst0 any more. Instead it uses udev and creates different names in /dev/tape/by-id/ directory. See my commit to mt-st: iustin/mt-st#8
I am maintain and use stenc in openSUSE with this patch - https://build.opensuse.org/package/show/Archiving:Backup/stenc

[jonasstein]

I did not understand the PR regarding the manpage. I close this ticket, because I think main part it is fixed with #48. Please open a new PR, if we missed something.