Read file using while loop in unix

Related Articles. How can you tell who modified a file in Unix? How do I run a program as a domain administrator? What happens when you update your operating system? Which office do I need for Windows 10? How do I install Chrome on elementary OS? Close Search for. I can't actually reproduce the problem when running the script as-is, but in any case you have other problems with your script.

Not tested, but I think your problem is that the pipe will be done after the while loop? As presented, that code snippet would print the second word from each line produced by the while Add a comment. Active Oldest Votes. As other have pointed out, awk redirection occur later. Improve this answer. Archemar Archemar Sign up or log in Sign up using Google. Cool Tip: Do not be a bore! I knew there was a way to do it without programming it.

Actually programming it would make it look cleaner. It is easy to do and the system calls are inside the executable. In introductory Unix, we experimented with standard input and standard output. Probably, one of the experiments you did was with the cat command:. Here, cat reads each line from standard input and writes the line to standard output.

It continues until the end-of-file condition is reached on file1 , then it stops. In shell programming, we can read a line from standard input using the read command. The read command succeeds so long as a line can be read. If the input reaches end-of-file, however, the next read fails.

This is exactly what happens in the cat command. This 'failure' status can be tested in a while statement like this:. If you type this at the terminal, it is kind of silly, as the read command will read a line from the keyboard.

Suppose we want to attach this to a file.