Common techniques for learning array in shell scripts

The subscript of the array in shell is 1 starting from 0 by default. Put the string in the array and get its length #! /Bin/bashstr & quot; AB -- nd & quot; array ($ str) length $ {# array [@]} echo $ lengthfor (i0; I & lt; $ length; I ++) doecho $ {array [$ I]} done execution...

The subscript of the array in shell starts from 0 by default.

1. Put the string in an array to obtain its length.

#! /Bin/bash
Str = "a B -- n d"
Array = ($ str)
Length =$ {# array [@]}
Echo $ length

For (I = 0; I <$ length; I ++ ))
Do
Echo $ {array [$ I]}
Done

Execution result:

[Oracle @ 99bill-as9 array] $ sh length. sh
4
A
B
-- N
D

Print string:

#! /Bin/bash
Str = "a B c"
For I in $ str
Do
Echo $ I
Done

Or:

#! /Bin/bash
Str = "a B c"
Array = ($ str)
For (I = 0; I <$ {# array [@]}; I ++ ))
Do
Echo $ {array [$ I]}
Done

Execution result:

A
B
C

2. When a string is separated by other characters

#! /Bin/bash

Str2 = "a # B # c"
A = ($ (echo $ str2 | tr '# ''' | tr-s ''))
Length =$ {# a [@]}

For (I = 0; I <$ length; I ++ ))
Do
Echo $ {a [$ I]}
Done
# Echo $ {a [2]}

Execution result:

A
B
C

3. Other operations on arrays

#! /Bin/bash
Str = "a B -- n dd"
Array = ($ str)
Length =$ {# array [@]}

# Ouput the first array element outputs the first element of the array.
Echo $ array

# Use subscript way access array access to array elements using the following method
Echo $ {array [1]}

# Output the array to Output this array
Echo $ {array [@]}

# Output in the array subscript for 3 the length of the element Output the length of the element marked as 3 in the array
Echo $ {# array [3]}

# Output in the array subscript 1 to 3 element: elements marked as 1 to 3 in the Output array
Echo $ {array [@]: 1: 3}

# Output in the array subscript greater than 2 elements Output the element whose subscript is greater than 2
Echo $ {array [@]: 2}

# Output in the array subscript less than 2 elements Output the element whose subscript is less than 2 in the array
Echo $ {array [@]: 2}

Execution result:

A
B
A B -- n dd
2
B -- n dd
-- N dd
A B

4. Traverse to access a string (separated by spaces by default. when the string is separated by other delimiters, refer to 2)

#! /Bin/bash
Str = "a -- m"
For I in $ str
Do
Echo $ I
Done

Execution result:

A
-- M

5. How to use echo to output a String str = "-n". because-n is a parameter of echo, the general echo "$ str" method cannot be output.
The solution can be:

Echo x $ str | sed's/^ x //'
Echo-ne "$ str \ n"
Echo-e "$ str \ n \ c"
Printf "% s \ n" $ str (this can also be done)

Author: "Zhu Ying's column"