Shell string and array summary

Blog home: http://blog.csdn.net/minna_d

1. Calculate the string length:

echo ${#str}

2. Truncate the string by character:
${word:begin:length}

3. With%, percent, #, # #对字符串的切割:
%: Right-to-left non-greedy match
Percent: greedy match from right to left
#: No greedy match from left to right
# #: Greedy match from left to right

Usage Example: ${str%.*} ${str%%.*} ${str#*.} ${str##*.}
PS: "." This is just an ordinary point, not an arbitrary character.

[Email protected] ~/q/data/tmp_data]# url= "hotel.qunar.com" [[email protected] ~/q/data/tmp_data]# echo ${url%.*} Hotel.qunar[[email protected] ~/q/data/tmp_data]# echo ${url%%.*}hotel[[email protected] ~/q/data/tmp_data]# echo ${ url#*.} Qunar.com[[email protected] ~/q/data/tmp_data]# echo ${url##*.} Com

4. Using IFS to split a string

IFS is a built-in field delimiter, here is a good description of ifs: http://blog.chinaunix.net/uid-22566367-id-381955.html

PS: Doubt, for str= ' ls-al ' This way I can't figure out what the generated is an array? Or is it a string ?

[[email protected] ~/q/data/tmp_data]# ifs= "\ n" [[email protected] ~/q/data/tmp_data]# str= ' ls-al ' [[Email  protected] ~/q/data/tmp_data]# echo $str total dosage 20drwxr-xr-x 2 root root 4096 January 9 13:52. drwxr-xr-x root root 409 6 January 7 19:53.. -rw-r--r--1 root root 12 January 9 13:51 1-rw-r--r--1 root root 10 January 9 13:52 2-rw-r--r--1 root root 28 January 9 13:51 2~[[email protected] ~/q/data/tmp_data]# echo ${str[@]} total usage 20drwxr-xr-x 2 root root 4096 January 9 13:52. drwxr-x R-x root root 4096 January 7 19:53. -rw-r--r--1 root root 12 January 9 13:51 1-rw-r--r--1 root root 10 January 9 13:52 2-rw-r--r--1 root root 28 January 9 13:51 2~[[email protected] ~/q/data/tmp_data]# [[email protected] ~/q/data/tmp_data]# echo ${str[*]} total usage 20drwxr-xr-x 2 root root 4096 January 9 13:52 drwxr-xr-x root root 4096 January 7 19:53.. -rw-r--r--1 root root 12 January 9 13:51 1-rw-r--r--1 root root 10 January 9 13:52 2-rw-r--r--1 root root 28 January 9 13:51 2~[[EMAIL&NBSp;protected] ~/q/data/tmp_data]# echo ${#str [@]}1 

Part II:

1. Calculate the length of the array:
${#array [@]}

2. List the array index:
${!array[*]} or ${!array[@]}

3. Print all the values in the array:
${array[*]} or ${array[@]}


Iterate through the array elements in 4.shell:
For STR in ${array[@]};
Do
Echo $str;
Done

5. Defining an empty array

Uset Array

Normal array:

1. Initialize:

The first type of initialization

[Email protected] ~/q/data/tmp_data]# array_origin= (1 2 3 4) [[email protected] ~/q/data/tmp_data]# echo ${#array_origin [@]} 4

The second type of initialization

[Email protected] ~/q/data/tmp_data]# arra_origin[0]=00[[email protected] ~/q/data/tmp_data]# arra_origin[1]=11[[ Email protected] ~/q/data/tmp_data]# arra_origin[2]=22[[email protected] ~/q/data/tmp_data]# arra_origin[3]=33

2. Access method:

[[email protected] ~/q/data/tmp_data]# for item in ${arra_origin[@]}; do Echo $item; done00112233

<strong>ps: How to iterate through an array in awk: </strong><span style= "color: #FF6666;" ><strong>i represents the key, not the value, do not avoid it!!</strong></span>

[Email protected] ~/q/data/tmp_data]# echo "1" | awk ' begin{array[1]=11; array[2]=22;array[3]=33;array[4]=44} {for (i in array) {print i}} ' 1234[[email protected] ~/q/dat a/tmp_data]# echo "1" | awk ' begin{array[1]=11; array[2]=22;array[3]=33;array[4]=44} {for (i in array) {print array[i]}} ' 11223344

Associative arrays:
The first type of display declaration is initialized:

[Email protected] ~/q/data/tmp_data]# declare-a ass_array_1

The second inline index value list is initialized:

[[email protected] ~/q/data/tmp_data]# ass_array_2= (["Host1"]= "192.168.1.23" ["Ip1"]= "192.168.1.23")

Assignment Value:

[Email protected] ~/q/data/tmp_data]# ass_array["host"]= "192.168.1.23" [[email protected] ~/q/data/tmp_data]# Ass_ array["IP"]= "192.168.1.23"

visit:
Query value by key

[Email protected] ~/q/data/tmp_data]# echo ${ass_array_1["host"]}192.168.1.23

View all keys

[[email protected] ~/q/data/tmp_data]# echo ${!ass_array_1[*]}host1 IP

View All value

[Email protected] ~/q/data/tmp_data]# echo ${ass_array[*]}192.168.1.23 192.168.1.23

Shell string and array summary