Bash loop through lines in file

Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Toggle navigation. Related posts:. How to Save Dictionary to File in Python. In this example, we will read the following text file and loop over lines. Our file name is filenames. Up to now, we have learned the basic syntax of for loop. There is also more formal for loop which is the same as C Programming language.

We need to provide start condition, iterate operation and end condition. In this example, we will use echo command to print from 1 to 5 with this for loop syntax. In some cases, we may need infinite loops. The infinite loop will never end except its process is killed. We will use C like for loop in order to create an infinite loop. During for loop, we may need to exit for given conditions if they occur. After the execution of the command, the value has been entered in each file we created.

Now open any text file. The file is not empty anymore. You can also check the data entered through the command. The first step is to write the data in the file and then display it. When you execute the command, the output will be as follow:. We know the loop for fetching the data and inserting the values, etc.

Now execute the backup command in the shell to see the backup of each file. Now to see the files on which this command is applied. We use the command as:. Now it is visible from the output that the detail of the files is shown. Date, file name, user name, and time also at which it was deleted. Also, you have an accurate copy of each file. It will fetch all the files with an extension of. With most shells, that's limited to space and tab. This function first determines the number of lines in the file, then uses sed to extract line after line, and passes each line as a single string argument to any given function.

I suppose this might get really inefficient with large files, but that hasn't been a problem for me so far suggestions on how to improve this welcome of course. Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How to loop over the lines of a file? Ask Question. Asked 10 years, 11 months ago.

Active 1 month ago. Viewed k times. Say I have this file: hello world hello world This program! Improve this question.