How do I read a while loop in Linux?

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 write a for loop in one line?

There are two ways of writing a one-liner for loop:

1. Method 1: If the loop body consists of one statement, simply write this statement into the same line: for i in range(10): print(i) .
2. Method 2: If the purpose of the loop is to create a list, use list comprehension instead: squares = [i**2 for i in range(10)] .

How do you loop through a directory in Linux?

To loop through a directory, and then print the name of the file, execute the following command: for FILE in *; do echo $FILE; done.

How do you read a file line by line in Unix while loop?

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.

How do you create a loop in Linux?

The syntax to loop through each file individually in a loop is: create a variable (f for file, for example). Then define the data set you want the variable to cycle through. In this case, cycle through all files in the current directory using the * wildcard character (the * wildcard matches everything).

How to execute a for loop in shell script?

The for loop execute a command line once for every new value assigned to a var (variable) in specified list (item1…itemN) i.e. repeat all statement between do and done till condition is not satisfied. The lists or values are normally: Create a shell script called testforloop.sh: #!/bin/bash for i in 1 2 3 4 5 do echo “Welcome $i times.” done

How to use for loop in Bash?

The for loop can be set using the numerical range. The range is specified by a beginning and ending number. The for loop executes a sequence of commands for each member in a list of items. A representative example in BASH is as follows to display multiplication table with for loop (multiplication.sh):

What are the rules of looping in C++?

Each and every loop must: 1 First, the variable used in loop condition must be initialized, then execution of the loop begins. 2 A test (condition) is made at the beginning of each iteration. 3 The body of loop ends with a statement that modifies the value of the test (condition) variable. 4 Repeatedly execute a block of statements. More

How do you execute a loop with a condition?

First, the variable used in loop condition must be initialized, then execution of the loop begins. A test (condition) is made at the beginning of each iteration. The body of loop ends with a statement that modifies the value of the test (condition) variable. Repeatedly execute a block of statements.