Set command output to variable bash

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Shell Programming and Scripting

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. When I run this script from the command line and pass it the arguments, I am not getting any output. How can one take the results of a command that needs to be run within a script, save it to a variable, and then output that variable on the screen? This character is called "backticks" or "grave accent". The first read foo will just skip header line, but in only one command, you will populate 7 different variables:. All pipes implies forks. Where another process have to be run, accessing disk, libraries calls and so on. Have a look at my answer to How do I split a string on a delimiter in Bash? And commands like date and bc could make many operations, line by line!! So we could use a long running background process to make many jobs, without having to initiate a new fork for each request. Of course, FD 5 and 6 have to be unused! From there, you could use this process by:. You may found my newConnector function on GitHub. Com or on my own site Note on GitHub: there are two files on my site. Function and demo are bundled into one file which could be sourced for use or just run for demo. The function myBc lets you use the background task with simple syntax, and for date:. From there, if you want to end one of background processes, you just have to close its fd :. Literally spent an hour trying to figure this out, trying all kinds of solutions! This is Not cool. Using heredocyou can simplify things pretty easily by breaking down your long single line code into a multiline one. Another example:. This is another way and is good to use with some text editors that are unable to correctly highlight every intricate code you create:. If the command that you are trying to execute fails, it would write the output onto the error stream and would then be printed out to the console. Some may find this useful. Please keep in mind that space is very important in Bash. So, if you want your command to run, use as is without introducing any more spaces. The following assigns the output of the command tr to L2. How are we doing? Please help us improve Stack Overflow. Take our short survey. Learn more. How do I set a variable to the output of a command in Bash? Ask Question. Asked 9 years, 3 months ago. Active 2 months ago.

How to use Variables in Bash Programming


By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It only takes a minute to sign up. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Setting jq output to a Bash Variable Ask Question. Asked 3 years ago. Active 9 days ago. Viewed 34k times. How can I change this so that the username variable gets assigned the output? Active Oldest Votes. I get Syntax error: redirection unexpected with or without the echo as the other answer suggests. In any case, even in zsh or bash which support that operator, that code doesn't make any sense. It redirects the stdin of echo which doesn't read it. It's a wonder how that answer managed to get 10 upvotes. This only works if you lose the "echo" on the second line. Anonymous Anonymous 41 1 1 bronze badge. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The Overflow How many jobs can be done at home? Featured on Meta. Community and Moderator guidelines for escalating issues via new response…. Feedback on Q2 Community Roadmap. Related 1. Hot Network Questions. Question feed.

How To Assign Output of a Linux Command to a Variable


By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It only takes a minute to sign up. You can't redirect command output to a variable in bash ; however you can assign the output of a command to a variable using command substitution. Note that counting lines of output from find is not a robust way to evaluate the number of matching files. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Asked 3 years, 2 months ago. Active 1 year, 7 months ago. Viewed 13k times. Rui F Ribeiro Active Oldest Votes. Also note the missing path in the find command. Kusalananda what do you mean? Serg Oh, just that find also requires a path to search. The OP didn't specify one. It's an additional problem in the question. Kusalananda If he is searching files in current directoryit's not necessary. At least GNU find assumes current path as. Serg Oh, the GNU strikes again. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The Overflow How many jobs can be done at home? Featured on Meta. Community and Moderator guidelines for escalating issues via new response…. Feedback on Q2 Community Roadmap. Related 0. Hot Network Questions. Question feed.

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When the user runs any command from the terminal then it shows the output if no error exists otherwise it shows the error message. Sometimes, the output of the command needs to be stored in a variable for future use. Shell command substitution feature of bash can be used for this purpose. How you can store different types of shell commands into the variable using this feature is shown in this tutorial. Bash commands can be used without any option and argument for those commands where these parts are optional. The following two examples show the uses of simple command substitution. The option and argument are mandatory for some bash commands. The following examples show how you can store the output of the command with option and argument into a variable. This command uses -c, -w and -l as option and filename as the argument to generate the output. Create a text file named fruits. Run the following commands to count and store the total number of words in the fruits. Create a text file named weekday. Create a bash file named cmdsub1. In this script, while loop is used to read the content of weekday. You can store the output of command substitution into any loop variable which is shown in the next example. Create a file named cmdsub2. How you can use multiple commands using pipe is shown in the previous example. But you can use nested commands in command substitution where the output of the first command depends on the output of the second command and it works opposite of the pipe command. If you know the path of the command then you can run the command by specifying the command path when using command substitution. The following example shows the use of command path. You can use the command line argument with the command as the argument in the command substitution.

Bash Scripting Tutorial - 2. Variables

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It only takes a minute to sign up. I'm trying to assign the output of a grep command to a variable in a bash script and the variable comes up empty. When I run the following:. If I run the grep command outside of the script and substitute the variables for real values I get the output I'm expecting. I think it's a quote issue. Try this one :. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Assigning output of grep to a variable Ask Question. Asked 7 years ago. Active 1 year, 4 months ago. Viewed 6k times. Here is a snippet of script. Use this script and add the values listed above. Rui F Ribeiro Something happened when I posted the command. Active Oldest Votes. GHugo GHugo 3 3 silver badges 9 9 bronze badges. Thanks for the reply, but I still get the same results. Please post some content for testing. Create a file called file. Then pass in the values file. And call it with file. Remember that xml langage is not a regular langage, so you might find case wich your sed exp will not work. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The Overflow How many jobs can be done at home? Featured on Meta. Community and Moderator guidelines for escalating issues via new response…. Feedback on Q2 Community Roadmap. Related 1. Hot Network Questions. Question feed.

Introduction to Bash Scripting 03 - Intro to Variables



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