[6280] in Release_7.7_team
Bringing bashrc and cshrc into sync
daemon@ATHENA.MIT.EDU (Jonathan Reed)
Thu Mar 12 17:42:07 2009
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From: Jonathan Reed <jdreed@MIT.EDU>
To: debathena@mit.edu, release-team@mit.edu
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Date: Thu, 12 Mar 2009 17:41:18 -0400
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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
