linux shell迴圈樣本

for迴圈樣本

for迴圈文法：

for VARIABLE in 1 2 3 4 5 .. Ndo         command1         command2         commandNdone
 
#!/bin/bashfor i in 1 2 3 4 5doecho "Welcome $i times"done

bash version 3.0+版本
#!/bin/bash for i in {1..5}do   echo "Welcome $i times"done
bash version 4版本 
#!/bin/bashecho "Bash version ${BASH_VERSION}..."for i in {0..10..2}  do     echo "Welcome $i times" done
含有“seq”命令的文法樣本
#!/bin/bashfor i in $(seq 1 2 20)do   echo "Welcome $i times"done
for迴圈的三個運算式
文法如下：
for (( EXP1; EXP2; EXP3 ))do         command1         command2         command3done
樣本如下：
#!/bin/bashfor (( c=1; c<=5; c++ ))do         echo "Welcome $c times..."done
效果：
Welcome 1 timesWelcome 2 timesWelcome 3 timesWelcome 4 timesWelcome 5 times
for的無限迴圈
#!/bin/bashfor (( ; ; ))do   echo "infinite loops [ hit CTRL+C to stop]"done
break條件陳述式
for I in 1 2 3 4 5do  statements1      #Executed for all values of ''I'', up to a disaster-condition if any.  statements2  if (disaster-condition)  then         break                #Abandon the loop.  fi  statements3          #While good and, no disaster-condition.done
下面的shell指令碼將通過在/ etc目錄中儲存的所有檔案。 for迴圈將放棄當/ etc / resolv.conf的檔案中找到。
#!/bin/bashfor file in /etc/*do         if [ "${file}" == "/etc/resolv.conf" ]         then                 countNameservers=$(grep -c nameserver /etc/resolv.conf)                 echo "Total  ${countNameservers} nameservers defined in ${file}"                 break         fidone
continue條件陳述式
for I in 1 2 3 4 5do  statements1      #Executed for all values of ''I'', up to a disaster-condition if any.  statements2  if (condition)  then         continue   #Go to next iteration of I in the loop and skip statements3  fi  statements3done
利用這個指令碼在命令列中指定的所有檔案名稱的備份。如果。bak檔案存在，它會跳過cp命令。
#!/bin/bashFILES="$@"for f in $FILESdo        # if .bak backup file exists, read next file         if [ -f ${f}.bak ]         then                 echo "Skiping $f file..."                 continue  # read next file and skip cp command         fi        # we are hear means no backup file exists, just use cp command to copy file         /bin/cp $f $f.bakdone