Standard output to file unix

How to redirect output to a file and stdout Ask Question. Asked 13 years ago. Active 2 days ago. Viewed k times. In bash, calling foo would display any output from that command on the stdout. Is there a way to redirect output to a file and have it display on stdout? Mike 2 2 silver badges 14 14 bronze badges. If someone just ended up here looking for capturing error output to file, take a look at - unix. That is, writing to the file is writing to stdout.

You are asking if it is possible to write both to stdout and to the terminal. WilliamPursell I'm not sure your clarification improves things :- How about this: OP is asking if it's possible to direct the called program's stdout to both a file and the calling program's stdout the latter being the stdout that the called program would inherit if nothing special were done; i. And maybe they also want to direct the called program's stderr similarly "any output from that command" might be reasonably interpreted to mean including stderr.

Add a comment. Active Oldest Votes. The command you want is named tee : foo tee output. Furthermore, if you want to append to the log file, use tee -a as: program [arguments Zoredache Zoredache There certainly are conditions where you might not want stderr as part of the output being saved to a file. When I answered this 5 years ago I assumed that the OP only wanted stdout, since he mentioned stdout in the subject of the post.

Ah sorry, I might have been a little confused. When I tried it I just got no output, perhaps it was all going to stderr. But if you want to attach a File to email you can use the input re-direction operator in the following format. The above examples were simple. Regular file, Directories, and even Devices are files. Your screen also has a File Descriptor. When a program is executed the output is sent to File Descriptor of the screen, and you see program output on your monitor.

If the output is sent to File Descriptor of the printer, the program output would have been printed. These files are always present whenever a program is run.

As explained before a file descriptor, is associated with each of these files. This could be especially important if that happened to be a terminal or device file. Also, your example is concerning. Never mix printf and cout, for starters, especially if you're going to play funny games with redirection.

Last edited by Corona; at PM.. Find all posts by Corona Shell Programming and Scripting. Thanks Lucas 4 Replies. Hi All, I am using centOS. For example Hello I read a lot of post related to this topic, but nothing helped me. I need to check output for possible errors. Hi, I would like to avoid re-directing line by line to a file.

Thanks in advance. Cheers Vj 1 Reply. So, if I have a script script. I know I can do:. This output is always followed by the filename. You can also use options for a more specific functionality. The introductory video should have given you a basic idea of how the commands mv , cp and rm , but there are some extra tricks that are good to know.

The cp -t command works in the same way. Now that we have a practical idea of this sections Unix commands, let's discuss the concept of standard streams. This will give you an idea to what exactly is going on when these commands are executed from the command line. Standard streams are streams of data that travel from where a program was executed, to the places where the program is processed and then back again.

It's important emphasize, that there are many streams of data in your computer, but the standard streams are the ones that the user has the most control over. There are 3 type of standard streams ; standard input stdin , standard output stdout and standard error stderror. We'll go through what each term means by using the command cat as an example. This will prompt you, the user, to give cat some input in the form stdin directly from your keyboard.

To exit the process, press Ctrl and d simultaneously. The command cat will then process the stdin that you've given it, and output it as what's called the standard output stdout.

In this case stdout is just whatever you typed, and it is by default connected to the terminal, which is why it appears there. If the process wasn't successful, a standard error stderror message will be outputted to the terminal instead. Depending on the error you made, different error messages can appear. If you, for example, type in ' eccho Hello' the stderror might return the error message 'bash: echho: command not found'.

The stderror is also connected to the terminal by default. Sometimes, nothing is outputted by the stdout and this is because some commands don't have a stdout. You've already experienced this in the last section with commands like mkdir, rmdir, rm, cd and so on. It's definitely a stream of data, but it's not the stdin.

The stdin is connected to your keyboard, and stdout or stderror outputs are directed to the terminal by default. We can, however, take control of these outputs by using redirectional operators, pipelines and the command tee.

Supplementary material on standard output and standard input Standard output Standard input. Operators are symbols which behave like functions within the Unix OS. In this section we'll be learning redirectional operators. This will redirect stdout of cat file1 to file2, which is the same as redirecting the file contents of file1 to file2. This means you have to be careful as to not overwrite your work when using it.

For example,. This is because the stdin is connected to the keyboard by default. To exit, simply hold the Ctrl key while pressing d.