[6281] in Release_7.7_team
Re: Bringing bashrc and cshrc into sync
daemon@ATHENA.MIT.EDU (Tim Abbott)
Thu Mar 12 23:39:17 2009
Date: Thu, 12 Mar 2009 23:38:18 -0400 (EDT)
From: Tim Abbott <tabbott@MIT.EDU>
To: Jonathan Reed <jdreed@mit.edu>
cc: debathena@mit.edu, release-team@mit.edu
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Message-ID: <alpine.DEB.1.10.0903121748270.22031@vinegar-pot.mit.edu>
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Seems like a reasonable strategy. There's some real work involved in
getting together the transition documents and making sure they're really
clear, but it seems doable.
The main question I'm not sure about is this: How do we expect users who
use both Debathena and Athena 9 machines during the transition interval to
configure their dotfiles? Perhaps it's the case that since we're simply
removing idempotent settings, if they want the setting back they can
simply add them to their dotfiles and it'll work fine on both platforms,
and have the right end result once Athena 9 stops existing...
-Tim Abbott
On Thu, 12 Mar 2009, Jonathan Reed wrote:
> After consulting with Oliver and Bill, with valuable input from Jacob, I would
> like to move forward on bringing the bash and tcsh configurations into sync.
> We're going to do this by punting a lot of legacy behavior on Debathena, and
> providing an easy way for users to revert if necessary. Athena 9 will not
> change, obviously. This is kind of a long e-mail, but please send me any
> feedback, *particularly if there will be any ill effects on tcsh users that I
> have not listed below*. I know there has been a flood of mail recently, but
> hopefully this will be the last on the dotfiles/shells topic. I'd like to
> move forward with this by early April, if not sooner.
>
> Here's the proposal:
>
> - We punt a lot of customizations from /usr/athena/lib/init/{cshrc,login} (see
> full list at the end of this mail), thus bringing cshrc largely into sync with
> bashrc.
> - We create sample cshrc.mine and bashrc.mine files (drafts in
> /mit/jdreed/debathena/) that users can prepend to their existing .cshrc.mine
> and .bashrc.mine files to emulate Athena 9 behavior.
> - At the beginning of the summer, before we start deploying Debathena in a
> widespread manner, we lert everyone and let them know about this change, and
> point them at a web page explaining what has changed, if/how it applies to
> them, and how to fix it.
> - Related to the previous item, the dotfiles for both shells should desupport
> the skip_lert option. Support has decided that this was a terrible idea and
> lert really should run every time. The average user only ever gets lerted
> _once_, at deactivation time, and there's no benefit to allowing users to skip
> this, since you can essentially skip it by running "lert -n".
>
> This has the following benefits: We get rid of a lot of cruft now, and bring
> bashrc and cshrc into sync. This is valuable, because the single largest
> source of people's Athena customizations is other Athena users. If we
> retained the current setup, tcsh users who switch to bash will be sad when
> some variables and aliases vanish and some behavior changes. Bash users who
> switch to tcsh to "get their account the same as their friend's account" will
> also be sad.
>
> This has the following effects on existing tcsh users under Debathena:
>
> - ~/.path files will be ignored, and users will get the default path unless
> they customize it in .cshrc.mine. ~/.path currently screws over new users at
> the rate of about one or two every year anyway, and it's time to stop
> supporting it.
> - Users who reference variables that we're punting (athena_path,
> athena_manpath, host, hosttype, bindir, cdpath) will be unable to login. Of
> these, athena_path and athena_manpath seem the most common, and those users
> already can't log in on Debathena, since athena_manpath isn't set, and
> athena_path is only set for ~/.path users.
> - Users who use the {s,t,}extend aliases in their .environment will lose those
> customizations (are there any of these users left?)
> - Users who use the extend alias elsewhere will get "command not found"
> - Keybindings for ^W, ^Z, and " " will change to their defaults.
> - cdpath won't be set, so users used to using this behavior will have to
> explicitly cd into subdirs of their home directory
> - noclobber and ignoreeof won't be set.
> - the prompt will change to the tcsh default (e.g. w20-575-1:~> ).
>
> This has the following effects on bash users under Debathena:
>
> - CDPATH will not be set
> - PS1 will be the default prompt (e.g. joeuser@w20-575-1:~$ )
>
> Here are the lines I propose to remove from /usr/athena/lib/init/cshrc, with
> commentary where appropriate:
>
> Line 12:
> > # Compatibility with older versions of Athena tcsh
> > set autolist=""
> > if ($?tcsh) then
> > bindkey "^W" backward-delete-word
> > bindkey "^Z" complete-word
> > bindkey " " magic-space
> >
> > endif
>
> Line 21:
> > # Set host type and hostname variables.
>
> > if (! $?ATHENA_HOSTTYPE) setenv ATHENA_HOSTTYPE "`/bin/machtype`"
> > if (! $?HOST) setenv HOST "`hostname`"
> > setenv HOSTTYPE "$ATHENA_HOSTTYPE"
> > set hosttype=$HOSTTYPE
> > set host=$HOST
>
>
> tcsh sets $HOST to `hostname` by default, so we can punt that.
> ATHENA_HOSTTYPE is only set in tcsh, not bash. Can we punt it and just keep
> $HOSTTYPE? I think we can also kill the two shell variables (host and
> hosttype).
>
> Line 67:
> > set bindir=arch/${ATHENA_SYS}/bin
>
> This should move into /usr/athena/lib/init/env_setup, which appears to be the
> only place it's used.
>
> Line 88:
> > # This "extend" alias and friends have been left in for backwards
> > # compatibility with old .environment files, just in case. The new
> > # add alias does not use them.
> > alias extend 'if (-d \!:2) if ("$\!:1" \!~ *"\!:2"*) set extendyes && \\
> > if ($?extendyes && $?verboseadd) echo \!:2 added to end of \$\!:1 && \\
> > if ($?extendyes) setenv \!:1 ${\!:1}:\!:2 && \\
> > unset extendyes'
> > alias sextend 'if (-d \!:2) if ("$\!:1" \!~ *"\!:2"*) set extendyes && \\
> > if ($?extendyes && $?verboseadd) echo \!:2 added to end of \$\!:1 && \\
> > if ($?extendyes) set \!:1=(${\!:1} \!:2) && \\
> > unset extendyes'
> > alias textend 'if (-d \!:2) if ("$\!:1" \!~ *"\!:2"*) set extendyes && \\
> > if ($?extendyes && $?verboseadd) echo \!:2 added to end of \$\!:1 && \\
> > if ($?extendyes) set \!:1=${\!:1}:\!:2 && \\
> > unset extendyes'
> >
>
> > # Run user environment customizations identified in your
> > # ~/.environment file. This is the place to include your own
> > # environment variables, attach commands, and other system wide
> > # setup commands. You can also cancel default behaviors listed
> > # above with "unsetenv" or "setenv". ~/.environment is not sourced
> > # if NOCALLS is set (i.e., if you selected the xlogin "Ignore your
> > # customizations" option when you logged in).
> >
> > if ((! $?NOCALLS) && (-r ~/.environment)) source ~/.environment
> >
> > unalias extend sextend textend
>
> Replace this with a single line sourcing ~/.environment, and remove the
> aliases.
>
> Line 116:
> > if ((! $?NOCALLS) && (-r ~/.path)) then
> > # Support .path files for compatibility.
> > set athena_path=($path)
> > source ~/.path
> > else
> > # Standard Athena path additions.
> > set path=(`/usr/bin/athdir $HOME` $path .)
> > endif
>
> Replace this with a single line setting $path to $path plus "athdir $HOME"
>
> Line 127:
> > # Set appropriate bin directory variable for this platform
> > # (e.g., vaxbin for VAXstations, decmipsbin for pMAXen, etc.; this will
> > # be included in actual searchpath as ~/$bindir -- e.g., ~/vaxbin):
> > set bindir=arch/${ATHENA_SYS}/bin
>
>
> bindir is set twice - once above, in the "ENVIRONMENT SETUP" section, and once
> here.
>
> Line 134:
> > # Set up standard C shell initializations
> >
> > set noclobber # Don't overwrite files with redirection
> >
> > if ($?prompt) then # For interactive shells only (i.e., NOT
> > rsh):
> > # Set prompt.
> > set promptchars="%#"
> > set prompt = "athena%# "
> > set cdpath = (~)
> > set interactive # Provide shell variable for compatability
> > endif
>
>
> Kill it and make users use the standard prompt and don't set noclobber.
>
> For /usr/athena/lib/init/login I propose we remove the "set ignoreeof" on line
> 56.
>
> -Jon
>
>
