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Feb 5, 2024 · Learn how to use the expr command to perform arithmetic, string, and logical operations in Linux. See examples of expr syntax, options, and functions for various expressions.
- Haroon Javed
- Contributor
May 15, 2019 · Learn how to use the expr command in Unix to evaluate expressions and perform basic operations, string operations, and regular expressions. See syntax, options, and examples of expr command in Linux.
In shell script we can substitute expr $a*$b with $(($a+$b)). But why not just with (($a+$b)), because in any resource it is written that (()) is for integer computation. So we use $(()) when there are variables instead of integer values do we? And what should we use instead of $(()) when variables can receive float values?
- For arithmetic, expr is archaic. Don't use it.*. $((...)) and ((...)) are very similar. Both do only integer calculations. ... $ a=2; b=3; echo...
- expr is old, but it does have one limited use I can think of. Say you want to search a string. If you want to stay POSIX with grep, you need to use...
- It seems that the following programs do more or less the same and they don't really differ. But that is not true. #!/bin/bash s=-1000 for (( i=0;...
Pattern matches return the string matched between \ ( and \) or null; if \ ( and \) are not used, they return the number of characters matched or 0. Exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null or 0, 2 if EXPRESSION is syntactically invalid, and 3 if an error occurred.
- Linux Expr Command
- Q1. How to Perform Arithmetic Operations Using expr?
- Q2. How to Perform Comparison Operations Using expr?
- Q3. How to Perform String-Related Operations Using expr?
- Conclusion
The tool's official documentation says it's used to evaluate expressions. Here's is the syntax of the expr command: Following are some Q&A-style examples that'll give you a good idea about how this tool works.
Suppose you want to add two numbers (say, 5 and 6), here's how you can do this using expr: Here's the above command in action: So you can see that the sum '11' was produced in the output. Please note that a single space on either side of the operator ('+' in this case) is mandatory. Otherwise, the expr command would produce the following output: wh...
The expr command also lets you perform comparison operations in various ways. For example, the following command (third in the screenshot below) will return ARG1 if it is neither null nor 0, otherwise ARG2. Please note that the backslash before pipe is used as an escape character as pipe is otherwise treated as a built-in shell operator. Similarly,...
The expr command also lets you perform several string-related operations. For example, to find length of a string, you can use the tool in the following way: In case the string contains spaces, you need to use the escape character. Moving on, you can also use expr to extract a substring in a given string. Here's the syntax: expr substr [string] [po...
As you'll likely agree, expr is a feature-rich command, but yet easy to understand and simple to use. Here, in this tutorial, we've tried to provide you information regarding most of the basic features it offers. Once you're done practicing these, you can head to the tool's man pageto learn more about it.
Jul 22, 2023 · Learn how to use the expr command for basic arithmetic operations and string manipulation in Bash scripts. See practical examples of calculating sum, subtraction, multiplication, division, remainder, increment, decrement, and average.
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Apr 23, 2024 · The expr command in Linux is a powerful tool for performing arithmetic and logical operations within the shell environment. However, like any command, it can sometimes encounter issues or may require optimization to ensure optimal performance.
