Shell Programming Basics

For C in a B C D E F g;do echo $c; Done sequentially output

For C in a B C D E F g;do tar czvf install.log. $c. tar.gz Install.log; Done

For C in {a.. g}; do echo $c; Done the same as above

Seq 1 10 columns of numbers

For i in {1..10}; do echo $i; Done

String variable instance
Str= ' I Love Linux. I love Unix too. '

Echo ${str} calculates string length

echo ${str:5} intercepts str from the fifth character to the end of the string

Echo ${str:7:5} intercepts the fifth character of Str starting with the seventh character

echo ${str#i Love} Delete the starting string

echo ${str#i*. Delete all characters starting from I to., Shortest match

echo ${str# #I *} Delete all characters from start I to., Longest match

Test is the meaning of testing

Shell Programming:
Single Branch
#!/bin/bash
Filename=/myshell/test1
If Test-f $filename; Then
Echo ' The file is exist. '
Fi

Dual Branch
#!/bin/bash
Filename=/myshell/test1
If Test-f $filename; Then
Echo ' The file is exist. '
Else
Echo ' The file is not exist. '
Fi

#!/bin/bash
Filename=/myshell/test2
If [-f $filename]; Then
Echo ' The file is exist. '
Else
Echo ' The file is not exist. '
Fi

Judge
#!/bin/bash
A=this
B=there
[$a! = $b]&&echo Yes | | Echo No

#!/bin/bash
Filename=/myshell/test3
Test-f $filename && echo ' exist ' | | echo ' not exist '
test-d $filename && echo ' exist ' | | echo ' not exist '
Test-r $filename && echo ' exist ' | | echo ' not exist '
Test-w $filename && echo ' exist ' | | echo ' not exist '
Test-x $filename && echo ' exist ' | | echo ' not exist '

Multi-Branch
#!/bin/bash
Echo ' please input your number. '
Read number
if [$number = = 1]; Then
echo ' Your input number is 1. '
elif [$number = = 2]; Then
echo ' Your input number is 2. '
elif [$number = = 3]; Then
echo ' Your input number is 3. '
Else
echo ' I dont know what do you input. '
Fi

Echo ' please input your hardware. '
Read HD
if [$HD = = CPU]; Then
Echo ' Your CPU info is. '
Cat/proc/cpuinfo
elif [$HD = = mem]; Then
Echo ' Your mem info is. '
Cat/proc/meminfo
elif [$HD = = hard]; Then
Echo ' Your harddisk info is. '
Df-h
Else
echo ' I dont know what do you input. '
Fi

Echo ' please input your number. '
Read number
Case $number in
1)
echo ' Your input number is 1. ';;
2)
echo ' Your input number is 2. ';;
3)
echo ' Your input number is 3. ';;
*)
echo ' I dont know what do you input. ';;
Esac

echo ' please input kemu. '
Read Kemu
Case $kemu in
Shuxue)
Echo ' Your input is shuxue. ';
中文版)
Echo ' Your input is 中文版 ';;
Yuwen)
Echo ' Your input is Yuwen. ';
*)
echo ' I dont know what do you input. ';;
Esac

While loop:

#!/bin/bash
# []-eq-ne-gt-ge-lt-le
# (()) = = = = > >= < <=
#program Summary

i=10
#while (($i >5));d o
While [$i-gt 5];d o
echo $i;
#if [$i-eq 8]; then
# echo ' The number is 8. '
#fi
((i--));
Done

Until cycle:

#!/bin/bash

a=10
Until (($a <0));d o
echo $a;
((a--));
Done

For loop:
#!/bin/bash
For ((i=1;i<=10;i++));d o
echo $i;
Done

#!/bin/bash
Echo ' please input an numer. '
Read number
For ((i=1;i<= $number; i++));d o
echo $i;
Done

Function:

#!/bin/bash
function print () {
echo "Your input is $x"
}

echo "This program would print you selection!"

Case $x in
"One")
print 1;;
"Both")
Print 2;;
"Three")
Print 3;;
*)
Print "Usage $ one|two|three";;
Esac

Shell Programming Basics