[sf-lug] printenv "vs." set [was: Re: shell, man(1) [was: ...

[Michael Paoli]

> From: "Alex Kleider" <akleider at sonic.net>
> Subject: Re: shell, man(1) [was: path name expansion]
> Date: Sat, 20 Aug 2016 08:59:29 -0700

> On 2016-08-19 11:13, Michael Paoli wrote:
>> $ man bash
>> ...
>> set [--abefhkmnptuvxBCEHPT] [-o option-name] [arg ...]
>> set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg ...]
>>       Without options, the name and value of each shell  variable  are
>>       displayed in a format that can be reused as input for setting or
>>       resetting the currently-set variables.  Read-only variables can-
>>       not  be  reset.  In posix mode, only shell variables are listed.
>>       The output is sorted according  to  the  current  locale.   When
>>       options  are specified, they set or unset shell attributes.  Any
>>       arguments remaining after option processing are treated as  val-
>>       ues for the positional parameters and are assigned, in order, to
>>       $1, $2, ...  $n.  Options,  if  specified,  have  the  following
>>       meanings:
>> ...
>> $ printenv | grep SHELL | grep -v '^XT'
>> SHELL=And why would you think this tells you the shell you're running?
>> $
>> What SHELL is set to in the environment, and the shell one is running,
>> are not necessarily the same ... hopefully obvious by my example
>> above.
>
> printenv and set do not appear to be doing the same thing.
> alex at X301n3:~/Test$ printenv | grep SHELL | grep -v '^XT'
> SHELL=/bin/bash
> alex at X301n3:~/Test$ set | grep '^BASH_VERSION='
> BASH_VERSION='4.3.11(1)-release'
> alex at X301n3:~/Test$ printenv | grep '^BASH_VERSION='

Yes, they're not doing the same thing.
RFTM.  :-)

bash(1)
...
>> set [--abefhkmnptuvxBCEHPT] [-o option-name] [arg ...]
>> set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg ...]
>>       Without options, the name and value of each shell  variable

printenv(1)
...
        Print the values of the specified environment VARIABLE(s)
...