Shell strings and Arrays

String:

1. Single quotes:

str = ' value '

Single-Quote String restrictions:

Any character in a single quotation mark is output as is, and the variable in the single-quote string is not valid;

Single quotation marks cannot appear in single quote strings (not after using escape characters for single quotes);

2. Double quotes:

str = "value is \" ${name}\ "\ n"

str = "value is, ${name}\n"

Advantages of double quotes:

You can have variables in double quotes.

Escape characters can appear in double quotes

3. Get string length :

1. String="ABCD"
2. echo ${#string} #输出 4

4. To extract substrings:

1. String="Alibaba is a great company"
2. echo ${string:1:4} #输出liba

5. To find a substring:

1. String="Alibaba is a great company"
2. echo ' expr index ' $string ' is '

Array:

1. Defined:

　Array_Name= (value0 value1 value2 value3)

2. Value:

${array_name[*]}

${array_name[@]}

Take all the elements

3. Get array Length:

1. # Gets the number of array elements
2. Length=${#array_name [@]}
3. # or
4. Length=${#array_name [*]}
5. # Gets the length of an array of individual elements
6. Lengthn=${#array_name [n]}

Shell strings and Arrays