Why 'script' utility require SHELL (and work fine under Linux)?

Oleksandr Gavenko gavenkoa@gmail.com
Sun Oct 16 17:08:00 GMT 2011

15.10.2011 0:47, Kaz Kylheku пишет:
>> So SHELL env var does not exported by bash...
>> Why?
> This is a bug in bash which hides broken behavior
> in the OS.
> Bash expects this to be an existing environment variable,
> and it usually is in normal Unix like operating systems.
> However, bash internally sets the variable if it is
> missing (without exporting it):
>  From "info bash".
> The full pathname to the shell is kept in this environment
> variable. If it is not set when the shell starts, Bash assigns to
> it the full pathname of the current user's login shell.
> It is correct not to export the variable. Bash might not be
> the user's shell, so it has no right to introduce itself as
> the SHELL to child processes.
> But, in fact, the shell does not own that variable at all
> and so it should not be setting it up even as an internal
> variable. The variable should stay unset to indicate
> that "there does not exist a configuration for the user's
> shell in this system".
> [...]
> Where does it come from on Linux? On the distro I have here,
> it is not exported by anything in /etc or my /home directory.
> Of course not. It comes from the "login" process which
> authenticates you and fetches your shell from the password
> file.
> Linux man page for "login":
> The value for $HOME, $SHELL, $PATH, $LOGNAME, and
> $MAIL are set according to the appropriate fields in
> the password entry.
> Cygwin sets HOME, and PATH, but not SHELL and LOGNAME.
Thanks for explanation. I set SHELL to /bin/bash under
control panel.

Also I set some another env var (place for info purpose):

   # Emacs parser of external program output
   # does not expect warnings from Cygwin...
   # To allow start X program anywhere when X started,
   # for example by Win+R
   # Where live all profiles...
   # This allow access to info files from Cygwin and native Emacs...
   # Take special attention to final colon.
   # This allow access to man files from Cygwin and native Emacs
   # (with cygwin-mount.el enabled)...
   # Take special attention to leading colon.

Also 2 year ago I write personal note about why set SHELL to /bin/bash:
if do not do so rxvt use sh as shell and ~/.bashrc was not read
and I lose my personal settings.

But when I switch to mintty I forget about this as mintty start bash by 

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