Frequent question: How use if in Linux?

How do I write an if statement in Linux?

Their description with syntax is as follows:

  1. if statement. This block will process if specified condition is true. …
  2. if-else statement. …
  3. statement (Else If ladder) …
  4. if) …
  5. Syntax: case in Pattern 1) Statement 1;; Pattern n) Statement n;; esac. …
  6. Example 2:

What is the use of IF command in Linux?

if is a command in Linux which is used to execute commands based on conditions. The ‘if COMMANDS’ list is executed. If its status is zero, then the ‘then COMMANDS’ list is executed.

How do I write an if statement in bash?

The syntax of an bash if statement

A short explanation of the example: first we check if the file somefile is readable (“if [ -r somefile ]”). If so, we read it into a variable. If not, we check if it actually exists (“elif [ -f somefile ]”).

What is in if loop in Linux?

The if statement allows you to specify courses of action to be taken in a shell script, depending on the success or failure of some command. It is a conditional statement that allows a test before performing another statement. The syntax for the simplest form is: if [ condition ] then block_of_statements fi.

What is if in bash script?

In bash scripting, as in the real world, ‘if’ is used to ask a question. The ‘if’ command will return a yes or no style answer and you can script the appropriate response.

What is the if statement?

An if statement is a programming conditional statement that, if proved true, performs a function or displays information. … In the example above, if the value of X were equal to any number less than 10, the program displays, “Hello John” when the script is run.

What is the purpose of in Unix?

Unix is an operating system. It supports multitasking and multi-user functionality. Unix is most widely used in all forms of computing systems such as desktop, laptop, and servers. On Unix, there is a Graphical user interface similar to windows that support easy navigation and support environment.

What does mean Linux?

For this particular case following code means: Somebody with user name “user” has logged in to the machine with host name “Linux-003”. “~” – represent the home folder of the user, conventionally it would be /home/user/, where “user” is the user name can be anything like /home/johnsmith.

How do I run a shell script?

Steps to write and execute a script

  1. Open the terminal. Go to the directory where you want to create your script.
  2. Create a file with . sh extension.
  3. Write the script in the file using an editor.
  4. Make the script executable with command chmod +x <fileName>.
  5. Run the script using ./<fileName>.
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