Shell for Loop and array application introduction _linux Shell

Reads a file, assigns each row to an array of variables, and prints it out with a for loop

Copy Code code as follows:

#!/bin/sh
I=1
sum= ' sed-n ' $= ' tmp.txt ' #计算文件的总行数
echo "$SUM"
While Read line
Todo
arr[$i]= "$line"
i= ' expr $i + 1 '
Done < Tmp.txt
echo "$i"
I=1
For i in ' seq $SUM ';d o
echo "${arr[$i]}"
Done

Attached: Shell array Supplemental knowledge

An array of declarations

1) Array[key]=value # Array[0]=one,array[1]=two
2) declare-a Array # array is treated as an array name
3) array= (value1 value2 value3 ...)
4) array= ([1]=one [2]=two [3]=three ...)
5) array= "One Two Three" # Echo ${array[0|@|*]}, treat the array variable as an array, but the array element has only the string itself

Second, access to the array

1) ${array[key]} # ${array[1]}

Three, delete the array

1) unset array[1] # Delete the first element in the array
2) unset Array # Delete entire array

Calculate the length of the array

1) ${#array}
2) ${#array [0]} #同上. ${#array [*]}, ${#array [@]}. Note the difference between the same #{array:0}