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 пиÑеÑ:
>
>> 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".
>
>
> `SHELL'
> 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):
SHELL=/bin/bash
# Emacs parser of external program output
# does not expect warnings from Cygwin...
CYGWIN=nodosfilewarning
# To allow start X program anywhere when X started,
# for example by Win+R
DISPLAY=:0
# Where live all profiles...
HOME=e:\home
# This allow access to info files from Cygwin and native Emacs...
# Take special attention to final colon.
INFOPATH='c:/opt/cygwin/usr/share/info;e:/home/usr/share/info;e:/bin/gnuwin32/info;e:/bin/gnuwin32/share/info:'
# This allow access to man files from Cygwin and native Emacs
# (with cygwin-mount.el enabled)...
# Take special attention to leading colon.
MANPATH=:/cygdrive/e/home/usr/share/man:/usr/share/man:/usr/local/share/man
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
default...
--
Problem reports: http://cygwin.com/problems.html
FAQ: http://cygwin.com/faq/
Documentation: http://cygwin.com/docs.html
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
More information about the Cygwin
mailing list