Bash concatenate variable name

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Bash concatenate variable name

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bash concatenate variable name

It only takes a minute to sign up. I need to concatenate two variables to create a filename that has an underscore. The CR character, when written to a terminal tells the terminal to move the cursor to the beginning of the line. TXT overriding the Hello. Performance doesn't seem to be an issue. You should use variables in lowercase it is the best practice.

So, your problem is not with how the variables are stick together, but with the contents of the vars. It seems reasonable to think that this:. One simple solution for ksh,bash,zsh is to remove all control characters from the read variable:.

Will get the correct value for name even if the other vars contain control characters. You can also use this: separate the separate vars with spaces and concatenate them using tr to remove the space.

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Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Concatenating two variables with an underscore Ask Question. Asked 6 years, 7 months ago. Active 2 years, 5 months ago. Viewed k times.

Usually the underscore first. Rhyuk Rhyuk 2 2 gold badges 7 7 silver badges 10 10 bronze badges. Probably your script contains carriage return characters. Yep that was it. Active Oldest Votes. Tim Tim 5, 13 13 silver badges 18 18 bronze badges. Windows formatting Your solution worked great after that. The first command mangles the value of the variable and the use of a command substitution and echo cannot possibly help. The second command was already given in the question.

I love it. Thanks for the solution! This works for me.In bash scripting, we can add or join two or more strings together, which is known as string concatenation. It is one of the common requirement for any programming language.

A special character or built-in function is applied to perform string concatenation. However, Bash does not contain any built-in function to combine string data or variables. The easiest method to perform string concatenation in bash is to write variables side by side.

For example, assume that we have two strings i. This concept is referred to as String Concatenation. This is the basic example of String Concatenation, and we do not need any extra operator or function in this method.

Another easy method is to use variables inside the string, which is defined with double-quotes. The string variable can be applied in any position of the string data. It will add new strings to the end of the string variable. In bash, printf is a function which is used to print and concatenate the strings. They should be used in such a way that the variable does not mix up with the literal string. Using underscore for concatenating the string in bash shell is one of the common tasks.

It is mostly used for assigning a name to the files. String Concatenation is one of the required features in the programming languages to generate meaningful output. Almost all the possible ways of joining the strings in bash are explained in this topic.

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Bash Variables

Mail us on hr javatpoint. Please mail your requirement at hr javatpoint. Duration: 1 week to 2 week. Bash Tutorial. Next Topic Bash Functions.

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Spring Boot. Selenium Py. Verbal A. Angular 7. Compiler D. Software E. Web Tech. Cyber Sec.Double quotation can be used to read the value of the variable. In this example, single quotation is used on one echo statement and double quotation is used on another echo statement.

Run the following commands from the terminal to check the output. Numeric values are taken as strings in BASH. So no arithmetic operation can be done by normal expression and it just combines the numeric values.

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If you write the expression with double first bracket then the arithmetic operation works properly. Run the following commands from the terminal. When you use bc command only for doing any arithmetic operation then fractional parts are omitted from the result.

bash concatenate variable name

You have to use -l option with bc command to get the result with fractional value. You can define variable in bash file by the same way which are mentioned in above examples. You have to create file with. Copy the following code in a text editor and save the file with bash extension. In this script, one string and one numeric variables are declared. In the following script, one global variable n and two local variables n and m are used. When the function addition is called then the value of the local variable n is taken for calculation but global variable n remains unchanged.

Array variable is used to store a list of data. The following example shows how you use of array variable in bash script. The elements of any array are separated by space in BASH. Here, an array of 6 elements is declared.

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There is no built-in function or property to count the total elements of the array. For loop is used here to iterate the array values.

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Reading array values and array values with key are shown in the next part of this script. To use BASH variables properly you need a clear concept on the declaration and use of variables. This tutorial will help you to get a clear idea on BASH variables. After exercising the above examples properly you will be able to use variables more efficiently in your bash scripts.

I am a trainer of web programming courses. I like to write article or tutorial on various IT topics. Variables work as temporary storage for any programming language.

The coder needs to have a clear concept of using different variables in the code. Variables are used to store specific data. 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.

So when any numeric value assigns to a variable then it will work as integer and when any text value assigns to a variable then it is string. The use of different types of BASH variables are described in this tutorial by using many examples. Example Declaring and reading string data using variable Run the following commands from the terminal.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I am trying to write a bash script. In this script I want user to enter a path of a directory.

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Then I want to append some strings at the end of this string and build a path to some subdirectories. For example assume user enters an string like this:. And if you want to use readline so you get completion and all that, add a -e to the call to read :. But, if no slash is used on either variable, it would be incorrect e. Without extended globing you can just use:. Reference: Shell Parameter Expansion. Learn more. How to concatenate two strings to build a complete path Ask Question.

Asked 7 years, 9 months ago. Active 3 months ago. Viewed k times. Reinstate Monica Please 8, 2 2 gold badges 22 22 silver badges 40 40 bronze badges. Hakim Hakim 7, 11 11 gold badges 31 31 silver badges 37 37 bronze badges.

bash concatenate variable name

What have you tried so far? Also, is part of your question about getting input from the user, and the other part about building the path?By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Learn more. Concat strings in a shell script [duplicate] Ask Question. Asked 8 years, 1 month ago. Active 1 year, 8 months ago. Viewed k times.

How can I concat strings in shell? Is it just Webnet Webnet It has to be next to the name and the value. Active Oldest Votes. Mariusz Jamro For various reasons. Ignacio Vazquez-Abrams Ignacio Vazquez-Abrams k gold badges silver badges bronze badges.

The Overflow Blog. Q2 Community Roadmap. The Unfriendly Robot: Automatically flagging unwelcoming comments. Featured on Meta.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I want to be able to create a variable name containing the first argument of the command and bearing the value of e.

If you can't use associative arrays e. I've been looking for better way of doing it recently. Associative array sounded like overkill for me. Look what I found:. Beyond associative arrays, there are several ways of achieving dynamic variables in Bash. Note that all these techniques present risks, which are discussed at the end of this answer.

You can simply store the name of the variable in an indirection variable, not unlike a C pointer. Unfortunately, there is no counterpart syntax for modifying the aliased variable.

Instead, you can achieve assignment with one of the following tricks. You have to carefully escape the right-hand side of the assignment, as it will be evaluated twice.

By contrast, all other methods below enforce it automatically. The read builtin lets you assign values to a variable of which you give the name, a fact which can be exploited in conjunction with here-strings:.

The IFS part and the option -r make sure that the value is assigned as-is, while the option -d '' allows to assign multi-line values. Because of this last option, the command returns with an non-zero exit code. Note that, since we are using a here-string, a newline character is appended to the value.

Since Bash 3. By contrast with the previous solutions, it just works, no extra effort is needed to escape things, to prevent splitting and so on. Since Bash 4. Just as in Method 1, the reference stores the name of the aliased variable, but each time the reference is accessed either for reading or assigningBash automatically resolves the indirection.

This does not avoid the pitfalls explained below, but at least it makes the syntax straightforward.

Concatenate string variables

All these aliasing techniques present several risks. The first one is executing arbitrary code each time you resolve the indirection either for reading or for assigning. The second risk is creating a cyclic alias.

bash concatenate variable name

As Bash variables are identified by their name and not by their scope, you may inadvertently create an alias to itself while thinking it would alias a variable from an enclosing scope. This may happen in particular when using common variable names like var.Today's Posts. Quick Links. Search Forums. Show Threads. Show Posts. Shell Programming and Scripting. Top Forums Shell Programming and Scripting concatenate variables.

Bash Scripting - Variables, Arrays, If-Then-Else

Registered User. Join Date: Feb I need to know how to concatenate variables in Debian. I am making a interactive script where it ask the user for info to add a user I pull the first letter from the first middle and last name into individual variables now i want to put them all in one variable so i can put it into useradd command This is what happening Code :. Last edited by jim mcnamara; at PM. Moderator Emeritus. Please use code tags, please do not double post, and consider reading the rules of the forum.

Your shell is bash, this gives the result of the first character from each of three variables concatenated Code :. Join Date: Nov If you want to do it like in your own example your left out a couple of things and there were too many spaces: Code :. Passing awk variables to bash variables. Running a script with multiple variables like 25 variables. Hi All, i have a requirement where i have to run a script with at least 25 arguements and position of arguements can also change.

Concatenate two variables and form the third variable. Hi Guys, I was scratching my head for this for half a day Help cannot concatenate Ksh variables?


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