Shulou(Shulou.com)06/02 Report--

condition test

1. Document testing

2, integer test

3. String and logic tests

If statement:

if single branch statement

if double branch statement

if multi-branch statement

if nested statement

Test command:

Tests whether a particular expression holds true. When the condition holds, the return value of the test statement is 0, otherwise it is another value.

Format 1: test conditional expression

Format 2:[conditional expression] //note spaces

file test

File testing refers to judging whether a file or directory corresponds to a given path name, or whether a file is readable, writable, executable, etc.

Common test operators:

-d: Test whether it is Directory

-e: Test whether the directory or file exists (Existing)

-f: Test whether it is a file (File)

-r: Test whether the current user has read permission

-w: Tests whether the current user has permission to write

-x: Tests whether the current user has permission to execute (eXcute)

Actual operation:

Format 1:

test -d /etc/sysconfig

echo $? (If the output value is 0, the condition is true)

Format 2:

[ -d /etc/sysconfig ]

echo $? (If the output value is 1, the condition is not true)

Compare integer values:

Format: [integer 1 operator integer 2 ]

Common test operators:

-eq =(Equal)

-ne: not equal

-gt: Greater Than

-lt: Lesser Than

-le: Less or Equal

-ge: Greater or Equal

string comparison

Format 1:[String 1 = String 2 ]

[String 1 ! = string 2 ]

Format 2:[ -z string]

Common test i operators:

=: String content identical

!=：String content is different,! expresses a contrary intention

-z: string content is empty

logic test

Format 1:[Expression 1 ] Operator [Expression 2 ]...

Format 2: Command 1 Operator Command 2...

Common operation options

-a or &&: logical and, meaning "and"

-o or|| logical OR logical OR

!：Logic no means "no."

If statement:

Single branch structure:

if conditional test operation

then

command sequence

fi

Double branch structure:

if conditional test operation

then

Command sequence 1

else

Command Sequence 2

fi

Multi-branch structure:

if conditional test operation

then

Command sequence 1

elif conditional test operation 2

then

Command Sequence 2

else

Command sequence 3

fi

If nested statements:

Objective: Run a race, enter the finals within 10 seconds, enter gender, prompt to enter men's group or women's group respectively, use multiple judgments, nested if to achieve

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.