Why does bash not quote variable with double quotes?

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Mandy Swaniawski asked a question: Why does bash not quote variable with double quotes?
Asked By: Mandy Swaniawski
Date created: Mon, Apr 5, 2021 12:33 PM
Date updated: Sat, May 21, 2022 4:17 PM

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Video answer: Quote wars: single vs double quoting in shell

Quote wars: single vs double quoting in shell

Top best answers to the question «Why does bash not quote variable with double quotes»

  • If we properly quoted our variable with double quotes ( " ), this would not happen: This time, Bash read the statement as if [ "" == "a" ] - a statement both easier on the eyes and the Bash compiler. No output is generated as clearly an empty string does not equal the letter a.

FAQ

Those who are looking for an answer to the question «Why does bash not quote variable with double quotes?» often ask the following questions:

💻 How to set variable with double quotes in bash?

  • Need help in fixing this bash script to set a variable with a value including double quotes. Somehow I am defining this incorrectly as my values foo and bar are not enclosed in double quotes as needed. What i need is account:"foo", profile:"bar" to be enclosed in double quotes.

💻 How do you escape a double quote in bash?

A double quote may be quoted within double quotes by preceding it with a backslash. If enabled, history expansion will be performed unless an ' ! ' appearing in double quotes is escaped using a backslash. The backslash preceding the ' !

💻 How to remove double quotes from string bash script debian?

Remove Double Quote from a String

  1. The first expression 's/^"//' will remove the starting quote from the string.
  2. Second expression 's/"$//' will remove the ending quote from the string.

Video answer: Linux shell quotes

Linux shell quotes

Your Answer

We've handpicked 24 related questions for you, similar to «Why does bash not quote variable with double quotes?» so you can surely find the answer!

How do i add a variable in bash?

To create a variable, you just provide a name and value for it. Your variable names should be descriptive and remind you of the value they hold. A variable name cannot start with a number, nor can it contain spaces. It can, however, start with an underscore.

How do i initialize a variable in bash?

When declaring a variable, its name should be in capital letters. We can declare a variable as a variable name followed by assigning operator (=) and the value, which may be a character or string or a number or a special character.

How do i save a variable in bash?

2 Answers. If it's storing for the sake of reading it in later (in a bash script), just use declare -p KEY and then source the file to read it in again. If you just want to store the value, use printf '%s\n' "$KEY" as you would do when you output any variable data. or whatever you need to output.

How do i set default variable in bash?
  1. To set a default value for a BASH variable, the syntax is: (good for setting default value for a BASH command line parameter)
  2. VARIABLE=${1:-DEFAULTVALUE} #set VARIABLE with the value of 1st Arg to the script, ...
  3. The following simple script illustrate this:
  4. tmpdir=/tmp.
How do i unexport a variable in bash?
  1. vech=Bus. Display the value of a variable with echo, enter:
  2. echo "$vech" Now, start a new shell instance, enter:
  3. bash. Now, display back the value of a variable vech with echo, enter:
  4. echo $vech…
  5. export backup="/nas10/mysql" echo "Backup dir $backup" bash echo "Backup dir $backup" ...
  6. export -p.

Video answer: Double, single and reverse quotes explained

Double, single and reverse quotes explained 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.
How to add path variable to bash file?
  • You can add path to any one of the following method: $HOME/.bash_profile file using export syntax. /etc/paths.d directory. The syntax is as follows: In this example, add /usr/local/sbin/modemZapp/ directory to $PATH variable.

Video answer: Linux terminal for beginners commands 6: using quotes

Linux terminal for beginners commands 6: using quotes How to avoid leaking a variable in bash?
  • In Bash if you export the variable within a subshell, using parentheses as shown, you avoid leaking the exported variables: The advantage here is that after you run the script from the command line, you won't see a $TESTVARIABLE leaked into your environment:
How to change an environment variable in bash?

How to unset environment variable in Bash?

  • Delete (or Unset) an Environment Variable. Sometimes you want to completely remove the variable from the environment. In order to remove or unset a variable from the environment, you can again use the env command with the -unset (-u) command line option. bash$ env -u NAME. Another command which does the same thing is the unset command. The unset is a posix command and should be available in all shells, but you never know.
How to export a variable in bash script?
  • The -p option in export command helps in printing out all the variables which are getting exported. Also, -n option removes the export property from subsequent NAMEs. Also, by default environmental variables of parent script is exported to child processes. Example of Bash Export Variable

Video answer: Shell scripting tutorial-26: escape sequences

Shell scripting tutorial-26: escape sequences How to print a variable while using bash?
  • Both the echo and the printf commands can be used to print a variable while using Bash. It entirely depends on your personal preference which of these commands you choose to use.
How to set variable in bash using setenv?
  • For instance, if you are inside the c shell, and you use setenv to set the following variable: We can then use the echo command to view the value of that variable: Our value, "myvalue", was returned. Now let's run bash as a subshell: and see if it knows the value of our variable MYVAR:
When to use environment variable in bash shell?
  • The environment variables are valid for the duration of the session. The shell variables apply only to the current instance of the shell and are used to set short-term working conditions.
When to use valid variable names in bash?
  • Valid variable names: hey x9 GRATUITOUSLY_LONG_NAME _secret When we write functions and shell scripts, in which arguments are passed in to be processed, the arguments will be passed int numerically-named variables, e.g. $1, $2, $3
Where is the prompt variable stored in bash?
  • Where the Prompt Variable is Stored. Your Bash prompt configuration is stored in your user account’s .bashrc file, which is at ~/.bashrc. So, if your username is bob, the file is at /home/bob/.bashrc. You can open the file to view the current Bash variable.
Which is the most used variable in bash?
  • The most commonly used data type of variables are integer, string, float, double and Boolean. The data type of any variable has to be defined at the time of variable declaration for strongly type programming languages. But BASH is a weakly typed programming language that does not require to define any data type at the time of variable declaration.
Can you check if a variable exists in bash?
  • You can't use if command to check the existence of declared variables in bash however -v option exists in newer bash, but it's not portable and you can't use it in older bash versions. Because when you are using a variable if it doesn't exists it will born at the same time.
How to calculate lengh of a variable in bash?
  • If you want to find out the lengh of a variable (how many characters) you can do the following: Make a variable equal to an expression. print out the result of the expression. Return the result of the expression. There are several ways in which to do arithmetic in Bash scripts. Double parentheses is the preferred method.

Video answer: Removing double quotes from csv file quoted strings

Removing double quotes from csv file quoted strings How to increment a variable inside a bash loop?
  • Add a comment. |. 0. Incrementing a variable can be done like that: _my_counter=$ [$_my_counter + 1] Counting the number of occurrence of a pattern in a column can be done with grep. grep -cE "^ ( [^ ]* ) {2}US". -c count.
How to use multiple variable for input in bash?
  • So, here the user must enter the values for P, N, R space or tab separated, like: (here we didn't bother escaping the spaces for R as the rest of the line after the third word would end-up in R anyway; the user would still need to escape a trailing space though).

Video answer: Unix & linux: how to add newlines into variables in bash script?

Unix & linux: how to add newlines into variables in bash script?