expect()
{
	echo expect "$@"
}

tool_var() {
        eval $1=\"\${$1:-$2}\"
        export $1
}

A="aaa bbb ccc"

unset B

tool_var        B       ${B:-"$A"}

expect '<aaa bbb ccc>'
recho "$A"
expect '<aaa bbb ccc>'
recho "$B"

eto_prepend() {
        eval $1=\'$2\''${'$1':+":"${'$1'}}'; export $1
}

foo=bar; export foo
eto_prepend foo baz
expect '<baz:bar>'
recho $foo
expect '<baz:bar>'
recho ${foo-"bar"}

aa='aaa bbb ccc'

expect '<aaa bbb ccc>'
recho ${zzz-"$aa"}
expect '<bar>'
recho ${zzz:-"bar"}
expect '<bar>'
recho "${zzz:-bar}"
expect '<bar>'
recho "${zzz:-"bar"}"

var=abcde
expect '<abcde>'
recho "${var:-xyz}"
expect '<abcde>'
recho "${var:=xyz}"
expect '<xyz>'
recho "${var:+xyz}"

set 'a b' c d e f
expect '<a b> <c> <d> <e> <f>'
recho ${1+"$@"}
expect '<a b>'
recho "${1-"$@"}"
expect '<a> <b>'
recho ${1-"$@"}
expect '<a b> <c> <d> <e> <f>'
recho "${1+$@}"
expect '<a b> <c> <d> <e> <f>'
recho "${1+"$@"}"

HOME=/usr/homes/chet
somevar=
expect "<$HOME>"
recho ${somevar:-~}
expect "<$HOME>"
recho "${somevar:-~}"
expect '<~>'
recho "${somevar:-"~"}"
expect '<\~>'
recho "${somevar:-\~}"
expect '<\ \~>'
recho "${somevar:-\ \~}"
expect '<\ \ \~>'
recho "${somevar:-\ \ \~}"

expect "<$HOME>"
recho ${somevar:-$HOME}
expect "<$HOME>"
recho "${somevar:-$HOME}"
expect "<$HOME>"
recho "${somevar:-"$HOME"}"
expect '<$HOME>'
recho "${somevar:-\$HOME}"
expect '<\ $HOME>'
recho "${somevar:-\ \$HOME}"
expect '<\ \ $HOME>'
recho "${somevar:-\ \ \$HOME}"

foo=bar
expect "<'bar'>"
recho "${foo+'$foo'}"
expect "<'bar'>"
recho "${fox='$foo'}"

P='*@*'
expect '<*@*>'
recho "${P%"*"}"
expect '<*@*>'
recho "${P%'*'}"

expect '<*@>'
recho ${P%"*"}
expect '<*@>'
recho ${P%'*'}

expect '<*@*>'
recho ${P%""}
expect '<*@*>'
recho ${P#""}

expect '<*@*>'
recho ${P#"$foobar"}
expect '<*@*>'
recho ${P%"$foobar"}

s1=abcdefghijkl
s2=efgh

first=${s1/$s2*/}
expect '<abcd>'
recho $first

last=${s1##$first}
expect '<efghijkl>'
recho $last

shift $#
UNAME_RELEASE=${1:-4.2MP}

RELEASE=`expr "$UNAME_RELEASE" : '[^0-9]*\([0-9]*\)'` # 4
case "$RELEASE" in
"")     RELEASE=0 ;;
*)      RELEASE=`expr "$RELEASE" + 0` ;;
esac            
REL_LEVEL=`expr "$UNAME_RELEASE" : '[^0-9]*[0-9]*.\([0-9]*\)'`    # 1
REL_SUBLEVEL=`expr "$UNAME_RELEASE" : '[^0-9]*[0-9]*.[0-9]*.\([0-9]*\)'` # 2

expect '<4> <2>'
recho $RELEASE $REL_LEVEL $REL_SUBLEVEL

b1()
{
	b2 ${1+"$@"}
}

b2()
{	
	recho $*
	recho $#
}

expect '<1>'
b1 ''

expect '<bar> <2>'
b1 bar ''

expect '<bar> <2>'
b1 '' bar

expect '<4>'
b1 '' '' '' ''

NL="\\
"

NNL="+$NL+"

expect '<--\> <-->'
recho --$NL--
expect '<--\^J-->'
recho "--$NL--"

expect '<--+\> <+-->'
recho --$NNL--
expect '<--+\^J+-->'
recho "--$NNL--"

expect '<-+\> <+-\> <->'
recho -$NNL-$NL-

set ''
expect '<xy>'
recho "$*xy"
expect '<xy>'
recho "x$*y"
expect '<xy>'
recho "xy$*"
expect '<>'
recho "$*"
expect nothing
recho $*

unset undef ; set ""

recho ${undef-"$zzz"}
recho x${undef-"$zzz"}
recho x${undef-"$@"}
recho ${undef-"$@"}
recho ${undef-"$zzz"}x
recho ${undef-"$@"}x
recho "$@"x
recho "$zzz"x
recho ${undef-}
recho ${undef-""}

yyy=""
recho "$xxx"x
recho "$yyy"x

set "" "abd" ""
recho "$@"x
recho "$@"$xxx

OIFS="$IFS"

arg=a,b,c,d,e,f

IFS=,

export z=$arg

eval z1=\"$arg\"

IFS="$OIFS"

recho $z
recho $z1

# should give an error
abc\=def

zz="a b c d e"
declare a=$zz

recho "$a"
recho $a

recho $(echo "foo$(echo ")")")

# test backslash escapes

recho \a
recho \\a

recho "\a"
recho "\\a"

recho '\a'
recho '\\a'

recho $(zecho \a)
recho $(zecho \\a)

recho $(zecho "\a")
recho $(zecho "\\a")

recho $(zecho '\a')
recho $(zecho '\\a')

recho `zecho \a`
recho `zecho \\a`

recho `zecho "\a"`
recho `zecho "\\a"`

recho `zecho '\a'`
recho `zecho '\\a'`

a=foo

recho \$a
recho \\$a

recho "\$a"
recho "\\$a"

recho '\$a'
recho '\\$a'

recho $(zecho `zecho \a`)
recho $(zecho `zecho \\a`)

recho $(zecho `zecho "\a"`)
recho $(zecho `zecho "\\a"`)

recho $(zecho `zecho '\a'`)
recho $(zecho `zecho '\\a'`)

# should echo G { I K }
recho ${abc:-G { I } K }

abc=hi

# should echo hi K }
recho ${abc:-G { I } K }

# should echo a*
unset foo
recho "${foo:-"a"}*"