Shell Script Process Control

4.1.3 Shell Process Control Statements

If condition judgment Statement

If ( expression ) #if (Variable in Array)

Statement 1

Else

Statement 2

Fi

Case one, test if the directory exists, does not exist then new (note that space must be between the brackets)

#!/bin/sh

#judge direxist

if [! -d/data/20140515];then

mkdir-p/data/20140515

Else

echo "This DIR isexist,please exit ..."

Fi

Logical operator parsing:

- F determine if a file exists Eg:if [-f filename]

- D determine if a directory exists Eg:if [-D dir]

-eq equals applies To: integer comparison

-ne not equal to: integer comparison

-lt less than applied to: integer comparison

-GT greater than applied to: integer comparison

-le less than or equal to: integer comparison

-ge greater than or equal to: integer comparison

-A Both sides were established ( and ) Logical Expression – a Logical Expressions

- o Unilateral Establishment ( or ) Logical Expression – o Logical Expressions

- Z empty string

Case three, multiple condition test judgment

#!/bin/sh

scores=80;

if [[$scores-GT 85]]; Then

echo "Very good!";

elif [[$scores-GT 75]]; Then

echo "good!";

elif [[$scores-GT 60]]; Then

echo "pass!";

Else

echo "No pass!";

Fi

Loop statement for

for variables inch string

Do

Statement 1

Done

case one, print seq Multiple Numbers

#!/bin/sh

For i in ' seq 15 '

Do

echo "NUMis $i"

Done

case two, find the relevant Log , and then bulk pack

#!/bin/sh

For i in ' Find/var/log-name "*.log" '

Do

TAR–CZF 2014log.tgz $i

Done

Looping Statements while

while conditional Statements

Do

Statement 1

Done

Case One, while Conditional Judgment Number

#!/bin/sh

I=1;

while [[$i-lt]];d o

echo $i;

((i++));

Done

case Two, while read a file's contents row by line

#!/bin/sh

While Read line

Do

Echo $line;

done</etc/hosts

Case SELECT statement

Case $arg in

PATTERN1)

Statement 1

;;

PATTERN2)

Statement 2

;;

*)

Statement 3

;;

Esac

Case one, create a selection parameter script

#!/bin/sh

Case $ in

Monitor_log)

Monitor_log

;;

Archive_log)

Archive_log

;;

*          )

echo "Usage:{$0 Monitor_log | Archive_log |help} "

;;

Esac

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Shell Script Process Control