Redirect all output to file [duplicate]

Question

This question already has an answer here:

• How can I redirect and append both stdout and stderr to a file with Bash? 6 answers

I know that in Linux, to redirect output from the screen to a file, I can either use the > or tee. However, I'm not sure why part of the output is still output to the screen and not written to the file.

Is there a way to redirect all output to file?

Answer 1

To get the output on the console AND in a file file.txt for example.

make 2>&1 | tee file.txt

Note: & (in 2>&1) specifies that 1 is not a file name but a file descriptor.

Answer 2

All POSIX operating systems have 3 streams: stdin, stdout, and stderr. stdin is the input, which can accept the stdout or stderr. stdout is the primary output, which is redirected with >, >>, or |. stderr is the error output, which is handled separately so that any exceptions do not get passed to a command or written to a file that it might break; normally, this is sent to a log of some kind, or dumped directly, even when the stdout is redirected. To redirect both to the same place, use:

command &> /some/file

EDIT: thanks to Zack for pointing out that the above solution is not portable--use instead:

*command* > file 2>&1 

If you want to silence the error, do:

*command* 2> /dev/null

Answer 3

Use >> to append:

command >> file

Answer 4

Use this - "require command here" > log_file_name 2>&1

Detail description of redirection operator in Unix/Linux.

The > operator redirects the output usually to a file but it can be to a device. You can also use >> to append.

If you don't specify a number then the standard output stream is assumed but you can also redirect errors

> file redirects stdout to file
1> file redirects stdout to file
2> file redirects stderr to file
&> file redirects stdout and stderr to file

/dev/null is the null device it takes any input you want and throws it away. It can be used to suppress any output.