Shell Common script Comparison

-B Returns True when file exists and is a block file

-C Returns True when file exists and is a character file

-D returns True when pathname exists and is a directory

-E Returns True when pathname specified file or directory exists

-F Returns True when file exists and is a regular file

-G returns True when the file or directory specified by pathname exists and the Sgid bit is set

-H Returns True when file exists and is a symbolic link file, which is not valid on some old systems

-K returns True when a file or directory specified by pathname exists and a "sticky" bit is set

-P Returns True when file exists and is a command pipe

-R when the file or directory specified by pathname is present and returned as true when it is readable

-S returns True when file size is greater than 0 o'clock

-U returns True when the file or directory specified by pathname exists and the SUID bit is set

-W Returns True when the file or directory specified by pathname exists and is executable. A directory that is accessed for its content is necessarily executable.

-O Returns True when the file or directory specified by pathname exists and the user specified by the valid user ID of the current process

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-eq equals

-ne is not equal to

-GT Greater than

-lt less than

-le less than or equal

-ge is greater than or equal to

-Z Empty string

= Two characters equal

!= two-character range

-N Non-empty string

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-e filename true if filename exists [-e/var/log/syslog]

-D filename True if filename is a directory [-d/tmp/mydir]

-F filename True if filename is a regular file [-f/usr/bin/grep]

-L filename True if filename is a symbolic link [-l/usr/bin/grep]

-R filename True if filename is readable [-r/var/log/syslog]

-W filename true if filename is writable [-w/var/mytmp.txt]

-X filename is true if filename is executable [-l/usr/bin/grep]

Filename1-nt filename2 is True if filename1 is newer than filename2 [/tmp/install/etc/services-nt/etc/services]

Filename1-ot filename2 is true if filename1 is older than filename2 [/boot/bzimage-ot Arch/i386/boot/bzimage]

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-Z String True if string length is zero [-Z $myvar]

-N String True [-N $myvar] If string length is Non-zero

string1 = string2 true if string1 is the same as string2 [$myvar = one Two three]

String1!= string2 True if string1 is different from string2 [$myvar!= one Two three]

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Num1-eq num2 equals [3-eq $mynum]

Num1-ne num2 Not equal to [3-ne $mynum]

Num1-lt num2 less than [3-lt $mynum]

Num1-le num2 less than or equal to [3-le $mynum]

NUM1-GT num2 is greater than [3-GT $mynum]

Num1-ge num2 greater than or equal to [3-ge $mynum]

Script Example:

#!/bin/bash

# This script prints a message about the your weight if you give it your

# Weight in kilos and hight in centimeters.

if [! $# = 2]; Then

echo "Usage: {GetProperty (Content)} Weight_in_kilos length_in_centimeters"

Exit

Fi

Weight= "{GetProperty (Content)}"

Height= "$"

idealweight=$[$height-110]

If [$weight-le $idealweight]; Then

echo "You are should eat a bit more fat."

Else

echo "You are should eat a bit more fruit."

Fi

# weight.sh 70 150

You are should eat a bit more fruit.

# weight.sh 70 150 33

Usage:./weight.sh Weight_in_kilos Length_in_centimeters

Position parameter {getproperty (content)}, $,..., $N, $ #代表了命令行的参数数量, {getproperty (content)} represents the name of the script.

The first parameter represents {GetProperty (Content)}, the second parameter represents $, and so on, and the total number of arguments exists $ #中, and the example above shows how to change the script and print out a message if there are fewer than 2 arguments or more.

Execute and view the situation.

# bash-x tijian.sh 60 170

+ weight=60

+ height=170

+ idealweight=60

+ ' [' 60-le 60 '] '

+ echo ' You should eat a bit more fat. '

You are should eat a bit more fat.

Where-X is used to check the execution of the script