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Editor to share with you the Linux command line and shell script programming example analysis, I believe that most people do not know much about it, so share this article for your reference, I hope you will learn a lot after reading this article, let's go to know it!

First script file

The code is as follows:

#! / bin/bash

Echo "This is my first bash code!"

Exit 0

Redirection symbol and Mathematical calculation

The code is as follows:

#! / bin/bash

Echo-n "The time and date are:"

Date

Spaces are not allowed before and after the value1=100 # equal sign

Value2=$value1

Echo-n "value1="

Echo $value1

Echo-n "value2="

Echo $value2

Ls-l | sort > out.txt # pipe symbol (|) and redirect output symbol >

Ls-l > > out.txt # redirect append output symbol > >

Echo-n "wc $str2"

Else

Echo "$str1

< $str2" fi if [ -n $str1 ] then echo "The string '$str1' is not empty" else echo "the string '$str1' is empty" fi #检查文件目录 if [ -d $HOME ] then echo "your Home dir exists" cd $HOME ls -a else echo "there's a problem with your HOME dir" fi pwfile=/etc/shadow if [ -f $pwfile ] then if [ -r $pwfile ] then tail $pwfile else echo "Sorry, I'm unable to reas the $pwfile file " fi else echo "Sorry, the file $pwfile doesn't exist" fi if [[ $USER == h* ]] then echo "Hello $USER" else echo "Sorry, I don't know you" fi 循环语句 代码如下: #!/bin/bash for file in /home/hanxi/* do if [ -d "$file" ] then echo "$file is a directory" elif [ -f "$file" ] then echo "$file is a file" fi done var1=10 while [ $var1 -gt 0 ] do echo $var1 var1=$[ $var1 - 1 ] done var1=100 until [ $var1 -eq 0 ] do echo $var1 var1=$[ $var1 - 25 ] done #文件数据的循环 IFSOLD=$IFS IFS=$'\n' for entry in `cat /etc/passwd` do echo "Values in $entry -" IFS=: for value in $entry do echo " $value" done done | more for file in /home/hanxi/* do if [ -d "$file" ] then echo "$file is directory" elif echo "$file is a file" fi done >

Output.txt

Read parameters

The code is as follows:

#! / bin/bash

Name= `basename $0`

Echo the commane entered is: $name

C_args=$#

Echo count args:$c_args

# take the last parameter

Echo the last parameter is ${! #}

Echo all parameter: $*

Echo all parameter: $@

Count=1

For param in "$@"

Do

Echo "\ $@ parameter # $count = $param"

Count=$ [$count + 1]

Done

# getopts

While getopts: ab:c opt

Do

Case "$opt" in

A) echo "Found the-an option"

B) echo "Found the-b option, with value $OPTARG"

C) echo "Found the-c option"

*) echo "Unknown option: $opt"

Esac

Done

Shift $[$OPTIND-1]

Count=1

For param in "$@"

Do

Echo "Parameter $count: $param"

Count=$ [$count + 1]

Done

Read-p "Please enter your age:" age

Echo age:$age

If read-t 5-p "Please enter your name:" name

Then

Echo "Hellp $name,welcome to my script"

Else

Echo

Echo "sorry, too slow!"

Fi

Read-N1-p "Do you want to continue [Y hand N]?" Answer

Case $answer in

Y | y) echo

Echo "fine, continue on..."

N | n) echo

Echo OK,Good bye

Exit

Esac

Echo "This is the end of the script"

Read-s-p "Enter your password:" pass

Echo

Echo "Is your password really $pass?"

# read files

Count=1

Cat for.txt | while read line

Do

Echo "Line $count: $line"

Count=$ [$count+1]

Done

Echo "Finished processing the file"

Redirect file descriptor

The code is as follows:

#! / bin/bash

# permanent redirection

Exec 9 > & 2

Exec 2 > testerror

Echo "this will in testerror" > & 2

Exec 2: 3

Exec 4 > &-

# create temporary files in / temp

Tmpfile= `mktemp-t tmp.XXXXXX`

Echo "The tempfile is located at:$tempfile"

Cat $tempfile

Rm-f $tempfile

# create a temporary folder

Tmpdir= `mktemp-d dir.XXXXXX`

Cd $tmpdir

Tempfile1= `mktemp temp.XXXXXX`

Ls-l

Cd..

# logging messages

A = `date | tee testfile;\

Cat testfile;\

Date | tee-a testfile;\

Cat testfile`

Signal processing.

The code is as follows:

#! / bin/bash

# signal processing

Trap "echo 'get a sign'" SIGINT SIGTERM

Trap "echo byebye" EXIT

Echo "This is a test program"

Count=1

While [$count-le 10]

Do

Echo "Loop # $count"

Sleep 10

Count=$ [$count+1]

Done

Echo "This is the end of the test program"

Trap-EXIT# remove capture

# Reverend running at background

#. / test6.sh &

# run a script without using a terminal

# nohup. / test6.sh &

# View Job

# jobs

# restart the job

# bg 2 (job serial number) / / backend

# fg 2max / Front desk

# priority

# nice-n 10. / test6.sh

# renice 10-p 25904 (process number)

# estimated time to run the at command

# at-f test6.sh 20:00

# batch command, which runs when the average system load is less than 0.8. You can set the time, which is better than at command.

# corn table can be set to run in a loop, in a format:

# min hour dayofmonth month dayofweek command

# run on the first day of each month:

# 12 16 * * 1 command

# run on the last day of each month:

# 12 16 * if [`date +% d = d tommorrow` = 01]; then; command

The use of functions

The code is as follows:

#! / bin/bash

# function

# use return values

Function func1

{

Read-p "Enter a value:" value

Echo $[$value * 2]

}

Result= `func1`

Echo "the new value is $result"

# pass parameters

Function func2

{

Echo $[$1 / 2]

}

Result= `func2 2 2`

Echo "the new result is $result"

# Local variables, recursive

Function func3

{

If [$1-eq 1]

Then

Echo 1

Else

Local temp=$ [$1-1]

Local result= `func3 $temp`

Echo $[$result*$1]

Fi

}

Read-p "Enter value:" value

Result= `func3 $value`

Echo "the factorial of $value is: $result"

# call the current directory to the function library

#. . / myfuncs

The above is all the content of the article "sample Analysis of Linux Command Line and shell scripting programming". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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