[6286] in Release_7.7_team
Re: Bringing bashrc and cshrc into sync
daemon@ATHENA.MIT.EDU (William Cattey)
Fri Mar 13 19:31:57 2009
In-Reply-To: <alpine.DEB.1.10.0903121748270.22031@vinegar-pot.mit.edu>
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Cc: Jonathan Reed <jdreed@mit.edu>, Tim Abbott <tabbott@mit.edu>
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From: William Cattey <wdc@MIT.EDU>
Date: Fri, 13 Mar 2009 19:30:44 -0400
To: debathena@mit.edu, release-team@mit.edu
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jdreed chatted with me about this in person yesterday, and the plan
seems pretty bulletproof to me.
I say let's go ahead and do it!
-Bill
On Mar 12, 2009, at 11:38 PM, Tim Abbott wrote:
> 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
>>
>>
