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Get the length of the string

The code is as follows:

Code:

% x = "abcd"

# method 1

Expr length $x

four

# method 2

% echo ${# x}

four

# method 3

% expr "$x": ". *"

four

# help from expr

# STRING: REGEXP anchored pattern match of REGEXP in STRING

Find substring

The code is as follows:

Code:

Expr index $x "b"

two

Expr index $x "a"

one

Expr index $x "b"

two

Expr index $x "c"

three

Expr index $x "d"

four

Get the substring

The code is as follows:

Code:

# method 1

# expr startpos length

Expr substr "$x" 1 3

Abc

Expr substr "$x" 1 5

Abcd

Expr substr "$x" 2 5

Bcd

# method 2

# ${x:pos:lenght}

% echo ${XRO 1}

Bcd

% echo ${XRO 2}

Cd

% echo ${xpurl 0}

Abcd

% echo ${XRV 0RV 2}

Ab

% pos=1

% len=2

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

Bc

Match regular expression

The code is as follows:

Code:

# print matching length

Expr match $x "."

one

Expr match $x "abc"

three

Expr match $x "bc"

0

Pinch the beginning and end of a string

The code is as follows:

Code:

% x=aabbaarealwwvvww

Echo'${x%w*w}'

Aabbaarealwwvv

Echo'${x%%w*w}'

Aabbaareal

Echo'${x##a*a}'

Lwwvvww

Echo'${x#a*a}'

Bbaarealwwvvww

Where # means pinch, because # on the keyboard is on the left side of $.

Where% means%, because% on the keyboard is on the right side of $.

A single represents a minimum match and two represents a maximum match.

In other words, when there are multiple matching schemes, choose the maximum length or the minimum length of the match.

Replacement of string

The code is as follows:

Code:

% x=abcdabcd

% echo ${x/a/b} # replaces only one

Bbcdabcd

% echo ${x//a/b} # replace all

Bbcdbbcd

You can't use regexp, only *? The way in which files are extended.

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