linux if multiple or conditions

You can compare variable with numbers using different methods in Linux and Unix shell. elif (else if) is used for multiple if conditions. It follows that syntactic units of the makefile, such as rules, may safely be split across the beginning or the end of the conditional. As an alternative, we can use the elif construct , shot for else if. If marks are less than 80 and greater or equal to 50 then print 50 and so on. You can use multiple If and AND conditions combined in this logical test. then For example, you might want to execute certain commands if the condition is true, and other commands if the condition is false. Welcome! Can anyone... (3 Replies) Discussion started by: mryuyu1111. Hello World: Your First Raspberry Pi Project. If expression with AND Condition; If expression with OR Condition; If expression with Multiple Conditions; Options for IF statement in Bash Scripting. /bin/bash message if the user is 21 years old or younger, the message You are too old! If there is a command-sequence that should optionally run based on whether a conditional expression is true, then the if/then statement can look as simple as this: if [[some condition ]]; then do_something fi. But to print the lines when all the provided PATTERN match, we must use AND operator. ORis used between two or multiple conditions. Comment. -lt – less than if [ “$age” -le 21 ] ; then Avoid using the old [..] test unless you specifically need POSIX-style portability. Here is a list of the file test operators for the bash shell: -e – file exists if [ “$age” -ge 21 ] ; then Welcome! [me@linux ~] $ touch myfile [me@linux ~] $ if [[-f myfile &&-r myfile ]]; then echo "File exists and is Readable. Here, The condition in the if statement often involves a numerical or string test comparison, but it can also be any command that returns a status of 0 when it succeeds and some nonzero status when it fails. Categories Blog, CentOS, Debian, Fedora, Kali, Linux, Mint, RedHat, Ubuntu Tags and logic, awk, boolean, not logic, or logic Post navigation. If the condition is true, the commands following the then keyword are executed. If that is not the case, the Sorry, you are not allowed to be here, you are too young! For example: #!/bin/bash Of course, too many nested levels can be unwieldy as well, so two conditions per test seems like a good balance to me. message is displayed. We shall check if the number is even or if it also divisible by 5. This statement is used to carry out certain commands based on testing a condition. It is a conditional statement that allows a test before performing another statement. In programming, conditions are crucial : they are used to assert whether some conditions are true or not.. Logical OR & AND operations are very useful where multiple conditions are used in our programs (scripts). As an alternative, we can use the elif construct , shot for else if. Grep OR Using -E. grep -E option is for extended regexp. In the following example, we shall use Bash OR logical operator, to form a compound boolean expression for Bash IF. Awk Regular Expression Commands and Examples. August 31, 2015. By joining our community you will … Jump to navigation Jump to search ← Exit command • Home • Dealing with case sensitive pattern → The case statement is good alternative to multilevel if-then-else-fi statement. Awk is a very popular text processing tool. Here is another version of the script to print the largest number among the three numbers. -gt – greater than By using the grep command, you can customize how the tool searches for a pattern or multiple patterns in this case. Recent Posts. The number that the user has entered is then assigned to the variable, echo “You are just the right age. Multiple Conditions # The logical OR and AND operators allow you to use multiple conditions in the if statements. The basic structure of the if statement looks like this: if [ conditional-expression ] This … Awk Text Split and Delimit Examples. A more compact way to write such statements with multiple conditions is the case method. These operators combine several true/false values into a final True or False outcome (Sweigart, 2015). 1.3 Compare integer values using (-gt) and (-lt) We can use the, UID (User Identifier) and GID (Group Identifier), Set the default permissions for newly created files, Find out more information about your system. if is a command in Linux which is used to execute commands based on conditions. export VAR_NM=abc.txt export CURR_DT=20131011 export PREV_DT=20131012 if && then echo "Yes" else echo "NO" fi It should return Yes but returning NO always.Appreciate any help. -x – file is executable The second score, listed in column D, must be equal to or exceed 30. -ge – greater than or equal to. echo “You are just the right age. Search multiple patterns with awk . You can grep multiple strings in … Understanding Test Conditions in Linux Shell Scripting. Check the below script and execute it on the shell with different-2 inputs. www.tutorialkart.com - ©Copyright-TutorialKart 2018, # and opertor used to form a compund expression. ... Beginners Guide to BASH—Conditions and Variables. Welcome!” In this version, instead of the nested if statements, we’re using the … -r – file is readable, One of the most commonly used programming constructs is the conditional execution, or the, First, the condition inside the brackets is evaluated. Use multiple -e option with grep for the multiple OR patterns. Using the IF with other functions together, in a complex formula, allows you to test multiple conditions and criteria. commands The ‘if COMMANDS‘ list is executed.If its status is zero, then the ‘then COMMANDS‘ list is executed.Otherwise, each ‘elif COMMANDS‘ list is executed in turn, and if its exit status is zero, the corresponding ‘then COMMANDS‘ list is executed and the if command completes. read age We can ask a user to enter his or her age, and then execute different commands, depending on the input: #!/bin/bash || is the operator used for AND boolean operation. 3 Replies. In this article, we are going to tackle very important topic: the test conditions. The test Command The test command is used to check file types and compare values. Bash is still one of the most used programming language, although we don't prefer bash for writing complicated scripts but for normal scripts such as taking backup for automating certain day to day tasks, bash is still preferred across Linux users. else A simple example that will help you understand the concept. Welcome!” In this topic, we shall provide examples for some mostly used options. The hunting dogs followed the scent of the fox. Suppose, you have a table with the results of two exam scores. Use multiple -e options in a single command to get multiple patterns to implement OR operations. I am analyzing one of the scripts written by another person.script is having multiple if conditions and everything are nested.The code is not formatted properly.Is there any way to identify in Unix to identify begin and end of a particular if block? -d – directory exists echo “File $file doesn’t exist.” The condition in the if statement often involves a numerical or string test comparison, but it can also be any command that returns a status of 0 when it succeeds and some nonzero status when it fails. For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. Leave now!” The first score, stored in column C, must be equal to or greater than 20. As we mentioned above, you can use the binary operators && (and) and | | (or) in the double brackets [[compound notation. To demonstrate if-then-else statement examples, I am using the text file named foxfile.txt, which stored in the folder /home/vin/test and the following are the contents of this file: foxfile.txt A quick brown Fox jumps right over the lazy dog. Syntax: test EXPRESSION. BASH script "if then" with multiple conditions User Name: Remember Me? OR is used between two or multiple conditions. 1 Syntax. A Simple if Condition. if either of the multiple provided strings are found, print the respective matched line. First, the condition inside the brackets is evaluated. And as per the previous comments, when using bash or ksh, it's recommended to use ((..)) for numerical tests, and [[..]] for string/file tests and complex expressions. Awk Text Split and Delimit Examples. Here our conditions is $1=="ismail" and reversed with ! In the above example, we are searching for pattern with OR condition i.e. fi. Password: Programming This forum is for all programming questions. if statements can check multiple conditions and provide multiple responses. These options are used for file operations, string operations, etc. 2. A logical condition is created, when two or more conditioned produce a single result based on them. Simply checking for four legs doesn't guarantee that you have a cow, but checking the sound it makes surely does.� The syntax for the simplest form is:Here, 1. It is easier to read and write. if - if else is a very useful conditional statement used to create decision trees.if - if else used to check the given situation or operations and run accordingly.For example, we can check the age of the person and act accordingly if over 60 or below 60. Here our conditions is $1=="ismail" and reversed with ! Here one condition result may also invert the result of a other condition. OR logical operator combines two or more simple or compound conditions and forms a compound condition. The if statement allows you to specify courses of action to be taken in a shell script, depending on the success or failure of some command. The basic structure of the if statement looks like this: if [ conditional-expression ] then commands else other-commands fi. How to Use the IF … If you use the grep command with -E option, … (6 Replies) Discussion started by: vamsi.valiveti. If the condition is true, make reads the lines of the text-if-true as part of the makefile; if the condition is false, make ignores those lines completely. OR logical operator combines two or more simple or compound conditions and forms a compound condition. With the grep -e option, only one parameter can be passed. Grep is a powerful utility available by default on UNIX-based systems. Similarly, in the third parameter type the value that will be displayed if your condition … Syntax : It enable you to match several values against one variable. First, the condition inside the brackets is evaluated. I was trying to write multiple conditions inside the if statement but its not working. Following truth table gives information about the returned value by OR logical operator for different valid operand values. Otherwise, the commands following the else keyword are executed. if [ -e $file ] Awk Regular Expression Commands and Examples. First condition is always checked but the second condition is checked only if first condition is returned false Let’s say that we want to test if a file exists, and then execute different commands based upon that condition. Linux if-then-else Condition Shell Script Examples. Comparing Multiple Conditions Thus far, everything has been comparing one thing against another, but what if you want to compare two conditions? You are currently viewing LQ as a guest. We can nest if statement , allowing for multiple conditions. Logical OR& ANDoperations are very useful where multiple conditions are used in our programs (scripts). echo “You are too young. One of the most commonly used programming constructs is the conditional execution, or the if statement. Test conditions are very important when it comes to making decisions. I thought the output should be True because there are + in the statement. -ne – not equal to If the condition is true, the commands following the then keyword are executed. By default when we search for a pattern or a … other-commands elif [ “$age” -ge 60 ] ; then Otherwise, the commands following the else keyword are executed. Bash boolean OR operator takes two operands and returns true if any of the operands is true, else it returns false. If the condition is true, the commands following the, echo “Sorry, you are not allowed to be here, you are too young!”, First, we ask a user to enter his/her age. The fi (if backward) keyword marks the end of the if block. fi. But it turns out to be False. That outcome says how our conditions combine, and that determines whether our if statement runs or not. Read and Ping IP address. This is similar to using the -a (and) and -o (or) in a single bracket. First, the condition inside the brackets is evaluated. Welcome!”, You can see that the script above displays the, Here is another example. else -w – file is writable NOT operator. Use multiple -e option in a single command to use multiple patterns for the or condition. NOT operator. if neither of the conditions above is true: Here is another example. When working with Bash and shell scripting, you might need to use conditions in your script.. -le – less than or equal to Notices: Welcome to LinuxQuestions.org, a friendly and active Linux Community. We can accommodate these with boolean … It returns true if any one of conditions returns as true. Condition is a comparison between two values.for compression you can use test or [expr] statements or even exist status can be also used.expression is defined as - an expression is nothing but combination of values,relational operator (>,,>) and mathematical operator (+,-,/).there are the following kinds of statements available in shell programming as decision making statements. When you will be doing some complex data analysis, you might be needed to analyze more than one conditions at a time. Categories Blog, CentOS, Debian, Fedora, Kali, Linux, Mint, RedHat, Ubuntu Tags and logic, awk, boolean, not logic, or logic Post navigation. For example, if an animal has four legs and goes "moo," it is probably a cow. In this Bash Tutorial, we learned the syntax of Bash OR logical operator and how to use it in preparing compound expression for conditional statements or looping statements.