#! /bin/bash
#
# cshtobash - convert csh aliases, environment variables, and variables to
#	      bash equivalents
#
# usage: cshtobash [filename]
#
# If filename is given, that file is sourced.  Note that csh always
# sources .cshrc.  To recreate your csh login environment, run
# `cshtobash ~/.login'.
#
# Inspired by (and some borrowed from) a similar program distributed with
# zsh-3.0.
#
# Chet Ramey
# chet@po.cwru.edu
#
trap 'rm -f $TMPFILE1 $TMPFILEa $TMPFILEe $TMPFILEv $TMPFILEco $TMPFILEci' 0 1 2 3 6 15

{ TMPFILE1=$(mktemp -t cb.1.XXXXXX) &&
  TMPFILEa=$(mktemp -t cb.a.XXXXXX) &&
  TMPFILEe=$(mktemp -t cb.e.XXXXXX) &&
  TMPFILEv=$(mktemp -t cb.v.XXXXXX) &&
  TMPFILEco=$(mktemp -t cshout.XXXXXX) &&
  TMPFILEci=$(mktemp -t cshin.XXXXXX)
} || exit 1

T=$'\t'

SOURCE="${1:+source $1}"

cat << EOF >$TMPFILEci
$SOURCE
alias >! $TMPFILEa
setenv >! $TMPFILEe
set >! /$TMPFILEv
EOF

# give csh a minimal environment, similar to what login would provide
/usr/bin/env - USER=$USER HOME=$HOME PATH=/usr/bin:/bin:/usr/ucb:. TERM=$TERM SHELL=$SHELL /bin/csh -i < $TMPFILEci > $TMPFILEco 2>&1

# First convert aliases

cat << \EOF >$TMPFILE1
mkalias ()
{
	case $2 in
	'')	echo alias ${1}="''" ;;
	*[#\!]*)
		comm=$(echo $2 | sed  's/\!\*/"$\@"/g
				       s/\!:\([1-9]\)/"$\1"/g
			               s/#/\#/g')
		echo $1 \(\) "{" command "$comm"  "; }"
		;;
	*)	echo alias ${1}=\'$(echo "${2}" | sed "s:':'\\\\'':")\' ;;
	esac
}
EOF

sed "s/^\([a-zA-Z0-9_]*\)$T\(.*\)$/mkalias \1 '\2'/" < $TMPFILEa >>$TMPFILE1

echo '# csh aliases'
echo

$BASH $TMPFILE1 | sed -e 's/\$cwd/\$PWD/g' \
		   -e 's/\$term/\$TERM/g' \
		   -e 's/\$home/\$HOME/g' \
		   -e 's/\$user/\$USER/g' \
		   -e 's/\$prompt/\$PS1/g'

# Next, convert environment variables
echo
echo '# csh environment variables'
echo

# Would be nice to deal with embedded newlines, e.g. in TERMCAP, but ...
sed -e '/^SHLVL/d' \
    -e '/^PWD/d' \
    -e "s/'/'"\\\\"''"/g \
    -e "s/^\([A-Za-z0-9_]*=\)/export \1'/" \
    -e "s/$/'/" < $TMPFILEe

# Finally, convert local variables
echo
echo '# csh variables'
echo

sed -e 's/'"$T"'/=/' \
    -e "s/'/'"\\\\"''"/g \
    -e '/^[A-Za-z0-9_]*=[^(]/{
	s/=/='"'/"'
	s/$/'"'/"'
	}' < $TMPFILEv |
sed -e '/^argv=/d' -e '/^cwd=/d' -e '/^filec=/d' -e '/^status=/d' \
	 -e '/^verbose=/d' \
	 -e '/^term=/d' \
	 -e '/^home=/d' \
	 -e '/^path=/d' \
	 -e '/^user=/d' \
	 -e '/^shell=/d' \
	 -e '/^cdpath=/d' \
	 -e '/^mail=/d' \
	 -e '/^home=/s//HOME=/' \
	 -e '/^prompt=/s//PS1=/' \
	 -e '/^histfile=/s//HISTFILE=/' \
	 -e '/^history=/s//HISTSIZE=/' \
	 -e '/^savehist=$/s//HISTFILESIZE=${HISTSIZE-500}/' \
	 -e '/^savehist=/s//HISTFILESIZE=/' \
	 -e '/^ignoreeof=$/s/^.*$/set -o ignoreeof # ignoreeof/' \
	 -e '/^ignoreeof=/s//IGNOREEOF=/' \
	 -e '/^noclobber=/s/^.*$/set -C # noclobber/' \
	 -e '/^notify=/s/^.*$/set -b # notify/' \
	 -e '/^noglob=/s/^.*$/set -f # noglob/' \


# now some special csh variables converted to bash equivalents
echo
echo '# special csh variables converted to bash equivalents'
echo

sed -e 's/'"$T"'/=/' < $TMPFILEv |
grep "^cdpath=" |
sed 's/(//
     s/ /:/g
     s/)//
     s/cdpath=/CDPATH=/'


sed -e 's/'"$T"'/=/' < $TMPFILEv |
grep "^mail=" |
sed 's/(//
     s/ /:/g
     s/)//
     s/mail=/MAILPATH=/' |
sed -e 's/MAILPATH=\([0-9][0-9][^:]*\)$/MAILCHECK=\1/' \
    -e 's/MAILPATH=\([0-9][0-9][^:]*\):\(.*\)/MAILCHECK=\1 MAILPATH=\2/'

exit 0
