read command in Linux system is used to read from a file descriptor. Basically, this command read up the total number of bytes from the specified file descriptor into the buffer. If the number or count is zero then this command may detect the errors.
What is the use of read command in Linux?
The Linux read command is used to read the contents of a line into a variable. This is a built-in command for Linux systems. Therefore, we do not need to install any additional tools. It is an easy tool to take user input when creating a bash script.
What is read in shell?
On Unix-like operating systems, read is a builtin command of the Bash shell. It reads a line of text from standard input and splits it into words. These words can then be used as the input for other commands.
What is read in bash?
read is a bash built-in command that reads a line from the standard input (or from the file descriptor) and split the line into words. The first word is assigned to the first name, the second one to the second name, and so on. The general syntax of the read built-in takes the following form: read [options] [name…]
What is the use of read in Unix?
read is a command found on Unix and Unix-like operating systems such as Linux. It reads a line of input from standard input or a file passed as an argument to its -u flag, and assigns it to a variable. In Unix shells, like Bash, it is present as a shell built in function, and not as a separate executable file.
How do I use Linux?
Its distros come in GUI (graphical user interface), but basically, Linux has a CLI (command line interface). In this tutorial, we are going to cover the basic commands that we use in the shell of Linux. To open the terminal, press Ctrl+Alt+T in Ubuntu, or press Alt+F2, type in gnome-terminal, and press enter.
How do you read a file in Linux?
From the Linux terminal, you must have some exposures to the Linux basic commands. There are some commands such as cat, ls, that are used to read files from the terminal.
Open the file using tail command.
- Open File Using cat Command. …
- Open File Using less Command. …
- Open File Using more Command. …
- Open File Using nl Command.
Why we use read in shell script?
Read is a bash builtin command that reads the contents of a line into a variable. It allows for word splitting that is tied to the special shell variable IFS. It is primarily used for catching user input but can be used to implement functions taking input from standard input.
How do I read a bash file?
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 I run a shell script?
Steps to write and execute a script
- Open the terminal. Go to the directory where you want to create your script.
- Create a file with . sh extension.
- Write the script in the file using an editor.
- Make the script executable with command chmod +x <fileName>.
- Run the script using ./<fileName>.
What is flag in Bash?
flag is the iterator variable here. In bash the do followed by while statement specifies starting of block which contains satement to be executed by while . The ending of block is specified by done .
What is Bash option?
Bash Shell -x Option. Invoking a Bash shell with the -x option causes each shell command to be printed before it is executed. This is especially useful for diagnosing problems with installation shell scripts.