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[ Linux Command Manual](#) The Linux `read` command is used to read values from standard input. The `read` builtin command is used to read a single line of data from standard input. This command can be used to read keyboard input, and when used with redirection, it can read a line of data from a file. ### Syntax read [name ...] **Parameter Description:** * `-a` followed by a variable, which will be treated as an array and assigned values, with space as the default delimiter. * `-d` followed by a delimiter character; only the first character after it is useful as the ending delimiter. * `-p` followed by a prompt message, which is printed before input. * `-e` enables command completion functionality during input. * `-n` followed by a number, defining the length of the input text, which is very practical. * `-r` disables backslash escaping. Without this option, `` acts as an escape character; with it, `` is treated as a normal character. * `-s` silent mode, where input characters are not displayed on the screen, for example, when entering a password during login. * `-t` followed by seconds, defining the wait time for input characters. * `-u` followed by a file descriptor, to read from that file descriptor, which can be newly opened with `exec`. ### Examples **1. Simple Read** #!/bin/bash# This will default to a new line echo "Enter website name: " # Read input from the keyboard read website echo "You entered: $website" exit 0 # Exit Test result: Enter website name: www. You entered: www. **2. The `-p` parameter allows specifying a prompt directly in the `read` command line.** #!/bin/bash read -p "Enter website name:" website echo "You entered: $website" exit 0 Test result: Enter website name:www. You entered: www. **3. The `-t` parameter specifies the number of seconds the `read` command waits for input. When the timer expires, `read` returns a non-zero exit status.** #!/bin/bashif read -t 5 -p "Enter website name:" website then echo "You entered: $website"else echo "nSorry, you timed out."fiexit 0 Run the program without input, wait 5 seconds: Enter website name:Sorry, you timed out 4. Besides timing the input, you can also use the **`-n`** parameter to set the **`read`** command to count input characters. When the number of input characters reaches the predetermined number, it exits automatically and assigns the input data to the variable. #!/bin/bash read -n1 -p "Do you want to continue [Y/N]?" answer case $answer in Y | y) echo "fine ,continue";; N | n) echo "ok,good bye";;*) echo "error choice";;esacexit 0 This example uses the `-n` option followed by the number 1, instructing the `read` command to exit as soon as it receives one character. As soon as a character is pressed as a reply, the `read` command immediately accepts the input and passes it to the variable, without needing to press Enter. Exit after receiving only 2 input characters: #!/bin/bash read -n2 -p "Please enter any two characters: " any echo "nThe two characters you entered are:$any"exit 0 Run the program and enter two characters: Please enter any two characters: 12The two characters you entered are:12 5. The **`-s`** option makes the data entered in the **`read`** command not displayed on the command terminal (in fact, the data is displayed, but the **`read`** command sets the text color to be the same as the background color). This option is commonly used when entering passwords. #!/bin/bash read -s -p "Please enter your password:" pass echo "nYour password is $pass"exit 0 Run the program and enter a password; it is not displayed: Please enter your password:Your password is tutorial **6. Reading a File** Each call to the `read` command reads "one line" of text from the file. When there are no readable lines left in the file, the `read` command exits with a non-zero status. How can data from a file be passed to `read`? Use the `cat` command and pipe its output directly to a `while` command containing the `read` command. The test file `test.txt` has the following content: 123456 tutorial Test code: #!/bin/bash count=1 # Assignment statement, no spaces cat test.txt | while read line # The output of the cat command is used as input for the read command; the value read by read is placed in linedo echo "Line $count:$line" count=$[ $count + 1 ] # Note the spaces inside the brackets. done echo "finish"exit 0 Execution result: Line 1:123Line 2:456Line 3:tutorial finish Using the **`-e`** parameter, the following example will output related filenames (existing in the directory) after entering the character **`a`** and pressing the **Tab** key: $ read -e -p "Enter filename:" str Enter filename:a a.out a.py a.pyc abc.txt Enter filename:a [ Linux Command Manual](#)