Fix error calling ps on AIX platforms

[kadler]

AIX ps does not support -w option in POSIX mode, only in Berkeley mode ('w'), but Berkeley mode doesn't support -o, so just remove the -ww option and hope for the best.

Fixes #21

[uranusjr]

Do you have the man entry available? I wonder if there are other flags we can use to keep w. That helps with some edge cases.

[uranusjr]

Also, is it possible to sniff out IBM systems in Python? Do os.name, sys.platform, or various calls from the platform module return interesting information?

[kadler]

Do you have the man entry available? I wonder if there are other flags we can use to keep w. That helps with some edge cases.

The latest man page is here: https://www.ibm.com/support/knowledgecenter/en/ssw_aix_72/com.ibm.aix.cmds4/ps.htm

I did not see an equivalent option for -w in POSIX mode or -o in Berkeley mode, unfortuantely :(

[kadler]

On AIX, os.name is 'posix', sys.platform is 'aix' followed by the major version (ie. 'aix6', 'aix7', ...).

We also run a variant of AIX inside of the IBM i OS. There, sys.platform will return 'os400' followed by the major version. I've included those platform checks in this PR.

[uranusjr]

The latest man page is here: https://www.ibm.com/support/knowledgecenter/en/ssw_aix_72/com.ibm.aix.cmds4/ps.htm

I did not see an equivalent option for -w in POSIX mode or -o in Berkeley mode, unfortuantely :(

Does ps wwl work? That would contain all the information we need (although more difficult to parse than -o).

[kadler]

Yes, here's a sample:

-bash-4.4$ ps wwl
     F S      UID    PID   PPID   C PRI NI ADDR  SZ  RSS   WCHAN    TTY  TIME CMD
240000 A      105 897903 897902   0  20 20    0 7124    0          pts/0  0:00 -bash 
200000 A      105 897904 897903   0  20 20    0 6792    0          pts/0  0:00 ps wwl

[uranusjr]

Ah, excellent. I’ll try to implement a parser for that format. Thanks for the help!

[uranusjr]

I just realised switching to ps wwl would likely affect #15. @sirn could you try the command out and see whether

1. ps prints a header row (but no actual content), and
2. the command returns 0?

[sirn]

From what I tried,

1. ✅ The command returns header row without content
2. ❌ The command returns 0

~ $ ssh freebsd.gemini 'uname -a'
FreeBSD freebsd 12.0-RELEASE FreeBSD 12.0-RELEASE r341666 GENERIC  amd64

~ $ ssh freebsd.gemini 'ps wwl || echo $?'
UID PID PPID CPU PRI NI VSZ RSS MWCHAN STAT TT  TIME COMMAND
1