Why do you use read and while in bash?

Carole Hand asked a question: Why do you use read and while in bash?
Asked By: Carole Hand
Date created: Tue, Mar 16, 2021 3:16 PM

Content

Top best answers to the question «Why do you use read and while in bash»

  • Loops using read allow you to iterate through lines of a file that is to be generated or already exists. We have a command or function (lhs) that can generate lines in a file that can be looped through using read and a while loop. We have a file (rhs) with lines that can be looped through using read and a while loop.

FAQ

Those who are looking for an answer to the question «Why do you use read and while in bash?» often ask the following questions:

💻 Do while in bash?

  • The Bash while loop takes the following form: while [CONDITION] do [COMMANDS] done The while statement starts with the while keyword, followed by the conditional expression. The condition is evaluated before executing the commands.

💻 Do while linux bash?

  • The Bash while loop takes the following form: while [CONDITION] do [COMMANDS] done The while statement starts with the while keyword, followed by the conditional expression. The condition is evaluated before executing the commands.

💻 Do while loops bash?

  • The while loop is used to performs a given set of commands an unknown number of times as long as the given condition evaluates to true. The Bash while loop takes the following form: The while statement starts with the while keyword, followed by the conditional expression. The condition is evaluated before executing the commands.

Your Answer

We've handpicked 22 related questions for you, similar to «Why do you use read and while in bash?» so you can surely find the answer!

How to enter read statements in bash?

  • To read the Bash user input, we use the built-in Bash command called read. It takes input from the user and assigns it to the variable. It reads only a single line from the Bash shell. Below is the syntax for its implementation.

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How to read multiple files in bash?

  • Open the two files on different file descriptors. Redirect the input of the read built-in to the descriptor that the file you want is connected to. In bash/ksh/zsh, you can write read -u 3 instead of read <&3. This snippet stops when the shortest file has been processed.

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What does read do in bash 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.

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When does bash read the.bash profile file?

  • The file ~/.bash_profile is read by bash when it is a login shell. That's what you get when you log in in text mode. When you log in under X, the startup scripts are executed by /bin/sh.

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Bash script how to read from a file?

  • Create a bash and add the following script which will pass filename from the command line and read the file line by line. The first argument value is read by the variable $1, which will include the filename for reading. If the file is available in the specified location then while loop will read the file line by line and print the file content.

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How do i read a file in bash?

  1. #!/bin/bash.
  2. file='read_file.txt'
  3. i=1.
  4. while read line; do.
  5. #Reading each line.
  6. echo "Line No. $ i : $line"
  7. i=$((i+1))
  8. done < $file.

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How do i read a filename in bash?

  1. #!/bin/bash.
  2. file=$1.
  3. while read line; do.
  4. #Readind each line in sequence.
  5. echo $line.
  6. done <read_file.txt.

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How do i read standard input in bash?

  1. #!/bin/bash.
  2. # using read command without any variable.
  3. echo "Enter name : "
  4. read.
  5. echo "Name : $REPLY"

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How do you read a variable in bash?

  1. #!/bin/bash.
  2. # Read the user input.
  3. echo "Enter the user name: "
  4. read first_name.
  5. echo "The Current User Name is $first_name"
  6. echo.
  7. echo "Enter other users'names: "
  8. read name1 name2 name3.

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How does the read command in bash work?

  • Let’s break down what will happen when the above code is submitted. cat /etc/passwd will read the contents of the file and pass it as input through the pipe. read command reads each line passed as input from cat command and stores it in the LREAD variable.

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How to read a config file in bash?

  • A very common example from posts here is /etc/default/grub. This file is used to set configuration options for GRUB, since grub-mkconfig is a shell script that sources it: (You could also do something like eval "$var=$value", but that's riskier than sourcing a script. You could inadvertently break that more easily than a sourced file.)

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How to read a csv file in bash?

  • For Bash versions 4 and above, we can also populate the array using the readarray command: readarray -t array_csv < input.csv This reads lines from input.csv into an array variable: array_csv. The -t option will remove the trailing newlines from each line.

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How to read a file in bash shell?

  • Bash Read File. There are many ways that we can use to read a file in Bash Shell Scripting. Some of the important methods are given below (Assuming, name of the file that we are reading is 'read_file.txt'): Reading File Using 'cat fileName' We can use the following syntax to take a print of the contents of the file to a terminal.

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How to read a jar file inside bash?

  • Hi All, I am having 7 jar files in a dir. abc like listed below bash-3.00$ cd abc bash-3.00$ ls 123.jar 23wdawd.jar dfsa23.jar dsa.jar wew234.jar adsd234234.jar dfsda423.jarNow i want to assign all this jar files to a variable in the below format ... 4. Shell Programming and Scripting

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How to read a word file in bash?

  • Splits on space tab and newline with # the default value of $IFS. If that words contain punctuactions and punctuations are words don't cause much trouble you could try this way. But, as usual, test.txt has been transformed by tr or sed or etc. in "1 word in line" list by tr or sed or etc. and read line by line.

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How to read output of a command bash?

  • To get the output of a command in an array, with one line per element, there are essentially 3 ways: With Bash≥4 use mapfile —it's the most efficient: mapfile -t my_array < < (my_command) Otherwise, a loop reading the output (slower, but safe):

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How to read the first line in bash?

  • 75 to read first line using bash, use readstatement. eg read -r firstline

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How to read user input from bash script?

  • To read the Bash user input, we use the built-in Bash command called read. It takes input from the user and assigns it to the variable. It reads only a single line from the Bash shell. Below is the syntax for its implementation. Follow the given examples to read user input from the Bash Script:

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How to read user input in bash script?

  • Read Command - Prompt User for Input in Bash Scripts The Linux read command is a bash builtin that is typically used to accept user input in a shell script. You can assign that input to a variable to be used for processing. There is however, a lot more to the read command.

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How to use read builtin in bash shell?

  • The read builtin command takes the following options: Store the words in an indexed array named array. Numbering of array elements starts at zero. Set the delimiter character to delim. This character signals the end of the line. If -d is not used, the default line delimiter is a newline. Get a line of input from an interactive shell.

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What should i read in my bash profile?

  • A typical .bash_profile will contain something like: so .bashrc can contain commands to be executed by either login or non-login shells. If you run bash -l rather than just bash, it should read your .bash_profile.

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How to use while true in bash?

  • bash while loop syntax The syntax is as follows: while [ condition ] do command1 command2 command3 done command1 to command3 will be executed repeatedly till condition is true.

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