What is do while script with example?

Shell Script While Loop Examples

  • while [ condition ] do command1 command2 commandN done.
  • while [[ condition ]] ; do command1 command1 commandN done.
  • while ( condition ) commands end.
  • #!/bin/bash c=1 while [ $c -le 5 ] do echo “Welcone $c times” (( c++ )) done.

How do you write a while loop in Shell?

ksh #!/bin/ksh # Script name: while. ksh num=1 while (( num < 6 )) do print “The value of num is: $num” (( num = num + 1 )) # let num=num+1 done print “Done.” $ ./while. ksh Value of num is: 1 Value of num is: 2 Value of num is: 3 Value of num is: 4 Value of num is: 5 Done.

How do you write a while loop in Linux?

In bash, while loops are written like this:

  1. while [condition] do [run commands] done.
  2. while [[ $found == false ]] do echo “Insert your password.” read password done.
  3. file=/etc/hosts while read -r line; do echo $line done < $file.

What is in while loop in shell script?

There is a condition in while. And commands are executed till the condition is valid. Once condition becomes false, loop terminates.

What is done in shell script?

Shell Scripting for loop

  • Keywords are for, in, do, done.
  • List is a list of variables which are separated by spaces. If list is not mentioned in the for statement, then it takes the positional parameter value that were passed into the shell.
  • Varname is any variable assumed by the user.

How do you read a file in shell?

How to Read a File Line By Line in Bash. The input file ( $input ) is the name of the file you need use by the read command. The read command reads the file line by line, assigning each line to the $line bash shell variable. Once all lines are read from the file the bash while loop will stop.

What does while IFS mean?

The while loop syntax IFS is used to set field separator (default is while space). The -r option to read command disables backslash escaping (e.g., \n, \t). This is failsafe while read loop for reading text files.

How do I read a while loop in Linux?

The following syntax is used for bash shell to read a file using while loop:

  1. while read -r line; do. echo “$line” ; done < input.file.
  2. while IFS= read -r line; do. echo $line; done < input.file.
  3. $ while read line; do. echo $line; done < OS.txt.
  4. #!/bin/bash. filename=’OS.txt’ n=1.
  5. #!/bin/bash. filename=$1. while read line; do.

How do you read a file in Shell?

What is the difference between C shell and Bourne shell?

CSH is C shell while BASH is Bourne Again shell. 2. C shell and BASH are both Unix and Linux shells. While CSH has its own features, BASH has incorporated the features of other shells including that of CSH with its own features which provides it with more features and makes it the most widely used command processor.