Shell for Loop

Similar to other programming languages, the shell supports A for loop.

The general format for A for loop is:

 for inch List  Do     command1    command2    ... CommandN Done

A list is a sequence of values (numbers, strings, and so on), each separated by a space. Each time the loop is passed, the next value in the list is assigned to the variable.

The in list is optional, if it is not used, the For loop uses the command-line positional parameters.

For example, sequentially output the numbers in the current list:

#!/bin/bashfor in12345    do Echo " The value is: $loop "  Done

Operation Result:

The value is:1Thevalue was:2Thevalueis:3Thevalueis:4 the value is:5

#!/bin/Bashnum=1 forStrinch 'This is a string' 'Test' Do  Echo$num Num=$[$num +1]   Echo$str DoneNum=1 forStrinch 'This is a string' Do  Echo$num Num=$[$num +1]   Echo$str Done

Operation Result:

1string2test1string

Show files starting with. Bash in the home directory:

#!/bin/bash $HOME/.bash* do  echo  $FILEDone  for in doing  echo  $FILE Done

Operation Result:

/root/. bash_history/root/. Bash_logout/root/. Bash_profile/ROOT/.BASHRC

Normal for loop

#!/bin/bashecho 'expr44' for ((i=110 ; i++) does   Echo $ (expr4)Done ~       

Method 1:
For variable in constant list; do some commands; done;

 for file  in $ (ls);  Do echo $file;  Done

 for inch 1 2 3 4 5;  Do Echo done;

Method 2:
For (variable initialization; condition judgment; variable self); do some commands; done;

 for ((i=0; i<doecho Done

 #!/bin/bashmax  =10  for  (I=0 ; i < MAX; I++ do   $i  done  for  ((I=0 ; i < $MAX; i++< Span style= "color: #000000;" ))  do  echo   $i  done  

#/bin/Bashmax=Ten for ((i=0; i < MAX; i++))do   Echo $ (expr $i \* $i)   echo $[$i * $i] Done

Shell for Loop