How to use For loop in shell script

How to use For loop in shell script

In this article we will see that How to use for loop in shell script.

The for loop operates on lists of items. It repeats a set of commands for every item in a list.



Syntax: 

for var in word1 word2 ... wordN
do
   Statement(s) to be executed for every word.
done





Here var is the name of a variable and word1 to wordN are sequences of characters separated by spaces (words). Each time the for loop executes, the value of the variable var is set to the next word in the list of words, word1 to wordN.

#! /bin/bash
#for loops
for VARIABLE in 1 2 3 4 5 ... N
do
      command1
      command2
      commandN
done

for VARIABLE in file1 file2 file3
do
      command1 on $VARIABLE
      command2
      commandN
done

for OUTPUT in $(Linux-or-unix-command-here)
do
     command1 on $OUTPUT
     command2 on $OUTPUT
     commandN
done

for (( EXP1; EXP2; EXP3; ))

do
   command1
   command2
   commandN
done


#Example:
for time in 1 2 3 4 5
do
      echo $time
done
 
for time in {1..10}
do
       echo $time
done

Example:-

for time in {1..10..4}
do 
     echo $time
done
     echo ${BASH_VERSION}
      for (( time=0; time<5; time++ ))
do
      echo $time
done





#list command with for loops

for command in pwd ls date
do
      echo " ...................... $command ...................."
      $command
done

#all the word will be consider in for loop
for item in *
do
    if [ -d $item ]
    then
          echo $item
    fi
done

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