%x="abcd"

#方法一

%expr length $x

4

# 方法二

%echo ${#x}

4

# 方法三

%expr "$x" : ".*"

4

# expr 的帮助

# STRING : REGEXP anchored pattern match of REGEXP in STRING

%expr index $x "b"

2

%expr index $x "a"

1

%expr index $x "b"

2

%expr index $x "c"

3

%expr index $x "d"

4

# 方法一

# expr <string> startpos length

%expr substr "$x" 1 3

abc

%expr substr "$x" 1 5

abcd

%expr substr "$x" 2 5

bcd

# 方法二

# ${x:pos:lenght}

%echo ${x:1}

bcd

%echo ${x:2}

cd

%echo ${x:0}

abcd

%echo ${x:0:2}

ab

%pos=1

%len=2

%echo ${x:$pos:$len}

bc

# 打印匹配长度

%expr match $x "."

1

%expr match $x "abc"

3

%expr match $x "bc"

0

%x=aabbaarealwwvvww

%echo "${x%w*w}"

aabbaarealwwvv

%echo "${x%%w*w}"

aabbaareal

%echo "${x##a*a}"

lwwvvww

%echo "${x#a*a}"

bbaarealwwvvww

%x=abcdabcd

%echo ${x/a/b} # 只替换一个

bbcdabcd

%echo ${x//a/b} # 替换所有

bbcdbbcd