學習 Shell Scripts

if [ 條件判斷式 ]; then 當條件判斷式成立時，可以進行的指令工作內容； fi 

[root@linux scripts]# vi sh06-2.sh #!/bin/bash # Program: # This program will show the user's choice # History: # 2005/08/25 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH read -p "Please input (Y/N): " yn if [ "$yn" == "Y" ] || [ "$yn" == "y" ]; then echo "OK, continue" exit 0 fi if [ "$yn" == "N" ] || [ "$yn" == "n" ]; then echo "Oh, interrupt!" exit 0 fi echo "I don't know what is your choise" && exit 0 

if [ 條件判斷式 ]; then 當條件判斷式成立時，可以進行的指令工作內容； else 當條件判斷式不成立時，可以進行的指令工作內容； fi 

if [ 條件判斷式一 ]; then 當條件判斷式一成立時，可以進行的指令工作內容； elif [ 條件判斷式二 ]; then 當條件判斷式二成立時，可以進行的指令工作內容； else 當條件判斷式一與二均不成立時，可以進行的指令工作內容； fi 

[root@linux scripts]# vi sh06-3.sh #!/bin/bash # Program: # This program will show the user's choice # History: # 2005/08/25 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH read -p "Please input (Y/N): " yn if [ "$yn" == "Y" ] || [ "$yn" == "y" ]; then echo "OK, continue" elif [ "$yn" == "N" ] || [ "$yn" == "n" ]; then echo "Oh, interrupt!" else echo "I don't know what is your choise" fi 

[root@linux scripts]# vi sh08.sh #!/bin/bash # Program: # Show "Hello" from $1.... # History: # 2005/08/28 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH if [ "$1" == "hello" ]; then echo "Hello, how are you ?" elif [ "$1" == "" ]; then echo "You MUST input parameters, ex> $0 someword" else echo "The only parameter is 'hello'" fi 

[root@linux ~]# netstat -tuln Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:199 0.0.0.0:* LISTEN tcp 0 0 :::80 :::* LISTEN tcp 0 0 :::22 :::* LISTEN tcp 0 0 :::25 :::* LISTEN 

[root@linux scripts]# vi sh09.sh #!/bin/bash # Program: # Using netstat and grep to detect WWW,SSH,FTP and Mail services. # History: # 2005/08/28 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH # 1. 先作一些告知的動作而已～ echo "Now, the services of your Linux system will be detect!" echo -e "The www, ftp, ssh, and mail will be detect! \n" # 2. 開始進行一些測試的工作，並且也輸出一些資訊囉！ testing=`netstat -tuln | grep ":80 "` if [ "$testing" != "" ]; then echo "WWW is running in your system." fi testing=`netstat -tuln | grep ":22 "` if [ "$testing" != "" ]; then echo "SSH is running in your system." fi testing=`netstat -tuln | grep ":21 "` if [ "$testing" != "" ]; then echo "FTP is running in your system." fi testing=`netstat -tuln | grep ":25 "` if [ "$testing" != "" ]; then echo "Mail is running in your system." fi 

[root@linux scripts]# vi sh10.sh #!/bin/bash # Program: # Tring to calculate your demobilization date at how many days # later... # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH # 1. 告知使用者這支程式的用途，並且告知應該如何輸入日期格式？ echo "This program will try to calculate :" echo "How many days about your demobilization date..." read -p "Please input your demobilization date (YYYYMMDD ex>20050401): " date2 # 2. 測試一下，這個輸入的內容是否正確？利用正規表示法囉～ date_d=`echo $date2 |grep '[0-9]\{8\}'` if [ "$date_d" == "" ]; then echo "You input the wrong format of date...." exit 1 fi # 3. 開始計算日期囉～ declare -i date_dem=`date --date="$date2" +%s` declare -i date_now=`date +%s` declare -i date_total_s=$(($date_dem-$date_now)) declare -i date_d=$(($date_total_s/60/60/24)) if [ "$date_total_s" -lt "0" ]; then echo "You had been demobilization before: " $((-1*$date_d)) " ago" else declare -i date_h=$(($(($date_total_s-$date_d*60*60*24))/60/60)) echo "You will be demobilized after $date_d days and $date_h hours." fi 

case $變數名稱 in "第一個變數內容") 程式段 ;; "第二個變數內容") 程式段 ;; *) 不包含第一個變數內容與第二個變數內容的其他程式執行段 exit 1 ;; esac 

[root@linux scripts]# vi sh08-2.sh #!/bin/bash # Program: # Show "Hello" from $1.... by using case .... esac # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH case $1 in "hello") echo "Hello, how are you ?" ;; "") echo "You MUST input parameters, ex> $0 someword" ;; *) echo "Usage $0 {hello}" ;; esac 

[root@linux scripts]# vi sh11.sh #!/bin/bash # Program: # Let user input one, two, three and show in screen. # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH echo "This program will print your selection !" # read -p "Input your choice: " choice # case $choice in case $1 in "one") echo "Your choice is ONE" ;; "two") echo "Your choice is TWO" ;; "three") echo "Your choice is THREE" ;; *) echo "Usage {one|two|three}" ;; esac 

function fname() { 程式段 } 

[root@linux scripts]# vi sh11-2.sh #!/bin/bash # Program: # Let user input one, two, three and show in screen. # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH function printit(){ echo -n "Your choice is " } echo "This program will print your selection !" case $1 in "one") printit; echo $1 | tr 'a-z' 'A-Z' ;; "two") printit; echo $1 | tr 'a-z' 'A-Z' ;; "three") printit; echo $1 | tr 'a-z' 'A-Z' ;; *) echo "Usage {one|two|three}" ;; esac 

[root@linux scripts]# vi sh11-3.sh #!/bin/bash # Program: # Let user input one, two, three and show in screen. # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH function printit(){ echo "Your choice is $1" } echo "This program will print your selection !" case $1 in "one") printit 1 ;; "two") printit 2 ;; "three") printit 3 ;; *) echo "Usage {one|two|three}" ;; esac 

while [ condition ] do 程式段落 done 

until [ condition ] do 程式段落 done 

[root@linux scripts]# vi sh12.sh #!/bin/bash # Program: # Use loop to try find your input. # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH while [ "$yn" != "yes" ] && [ "$yn" != "YES" ] do read -p "Please input yes/YES to stop this program: " yn done 

[root@linux scripts]# vi sh12-2.sh #!/bin/bash # Program: # Use loop to try find your input. # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH until [ "$yn" == "yes" ] || [ "$yn" == "YES" ] do read -p "Please input yes/YES to stop this program: " yn done 

[root@linux scripts]# vi sh13.sh #!/bin/bash # Program: # Try to use loop to calculate the result "1+2+3...+100" # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH s=0 i=0 while [ "$i" != "100" ] do i=$(($i+1)) s=$(($s+$i)) done echo "The result of '1+2+3+...+100' is ==> $s" 

for (( 初始值; 限制值; 執行步階 )) do 程式段 done 

[root@linux scripts]# vi sh14.sh #!/bin/bash # Program: # Try do calculate 1+2+....+100 # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH s=0 for (( i=1; i<=100; i=i+1 )) do s=$(($s+$i)) done echo "The result of '1+2+3+...+100' is ==> $s" 

for $var in con1 con2 con3 ... do 程式段 done 

[root@linux scripts]# vi sh15.sh #!/bin/bash # Program: # Using for .... loop to print 3 animal # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH for animal in dog cat elephant do echo "There are ""$animal""s.... " done 

[root@linux scripts]# vi sh16.sh #!/bin/bash # Program: # let user input a directory and find the whole file's permission. # History: # 2005/08/29 VBird First release PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin export PATH # 1. 先看看這個目錄是否存在啊？ read -p "Please input a directory: " dir if [ "$dir" == "" ] || [ ! -d "$dir" ]; then echo "The $dir is NOT exist in your system." exit 1 fi # 2. 開始測試檔案囉～ filelist=`ls $dir` for filename in $filelist do perm="" test -r "$dir/$filename" && perm="$perm readable" test -w "$dir/$filename" && perm="$perm writable" test -x "$dir/$filename" && perm="$perm executable" echo "The file $dir/$filename's permission is $perm " done