# shtype - determine shell type (hs '96, 1.5)
# Heiner Steven (heiner@hsysnbg.nbg.sub.org), Public Domain.
#
# Note: this script *must* start with a '#' character, because otherwise
#       "csh" may use "sh" to run it.
#
# Knows sh, ksh, ksh93, csh, tcsh, bash, zsh
#
# Thanks to
#	Dave Plonka <dev_dp@mfa.com>	(BSH)
#

# Check for Bourne shell or C shell dialect
set x = 1
test "$x" = 1 && goto CSH

# Bourne shell dialect

# Don't use external commands
PATH=;   export PATH

# ASH (FreeBSD/NetBSD sh) has a non-standard "setvar" command
# This test has to be the first, because otherwise ASH would
# terminate this script with the next test.
x=`(a=; setvar a b; echo $a) 2>/dev/null`
if [ X"$x" = Xb ]
then
    echo ASH
    exit 0
fi

# The standard Bourne shell does not know how to remove parts
# of a variable with ${VAR%%pattern}.
x="A.B"
x=`(echo ${x%%.*}) 2>/dev/null`
if [ "$x" = A ]
then
    # bash/zsh or ksh?
    # bash/zsh use $[...] for arithmetic evaluation.
    x=`(echo $[0+1]) 2>/dev/null`
    if [ "$x" = 1 ]
    then
	# zsh tests with ${+x} if variable x is set
	x=0
	x=`(echo ${+x}) 2>/dev/null`
	if [ "$x" = 1 ]
	then
	    echo "ZSH $ZSH_VERSION"
	else
	    echo "BASH $BASH_VERSION"
	fi
    else
	# ksh or ksh93?
	# ksh93 can extract substrings from a variable.
	x=AB
	x=`(echo ${x:1:1}) 2>/dev/null`
	if [ "$x" = B ]
	then
	    echo "KSH93 ${.sh.version}"
	else
	    # ksh or POSIX shell? POSIX shell treats prefix 0 as octal
	    res="$((010+10))"
	    if [ ${res:=0} -eq 18 ]
	    then
		echo KSH "(POSIX)" ${KSH_VERSION-$KSH_VERSION}
	    elif [ $res -eq 20 ]
	    then
		echo KSH ${KSH_VERSION-$KSH_VERSION}
	    else
		exit 1	# unknown ksh-similar shell
	    fi
	fi
    fi
else
    echo BSH
fi
exit 0

CSH:
# C-Shell dialect

# tcsh has a bindkey command
if { bindkey >& /dev/null } then
    echo "TCSH $version"
else
    echo CSH
endif
exit 0