On 06/21/2011 06:42 AM, Dominic Ringuet wrote:
> On Tue, Jun 21, 2011 at 8:22 AM, Webmaster<[email protected]>  wrote:
>> For example:
>> ls -l /usr/bin | more>  redirect_test.log 2>&1 (BLFS 6.3 Page 37)
>> What does "2>&1" mean?
> 2 is stderr
>> is a redirector
> &1 is stdout
>
> ===>Without it, both normal output and errors will be printed in the file;===<
did you really mean this?
according to this test, your statement is not true.

nolan@retired:~$  ls -l /not/a/file > yes.file
ls: cannot access /not/a/file: No such file or directory
nolan@retired:~$ cat yes.file
nolan@retired:~$ ls -l yes.file
-rw-r--r-- 1 nolan nolan 0 2011-06-21 10:08 yes.file
nolan@retired:~$ ls -l /not/a/file > yes.file 2>&1
nolan@retired:~$
nolan@retired:~$ cat yes.file
ls: cannot access /not/a/file: No such file or directory
nolan@retired:~$ ls -l yes.file
-rw-r--r-- 1 nolan nolan 57 2011-06-21 10:11 yes.file
nolan@retired:~$

Have I missed something?

with it, normal output goes in the file and error is on the screen.
> (unless standard output goes somewhere else)
>
> Examples:
>
> ls -al /usr>  test.log 2>&1
> * the content of /usr will goes in test.log
>
> ls -al /usr>  test.log
> * the content of /usr will goes in test.log
>
> So far, there are no errors, the behavior is the same in both
> instances. The expression becomes meaningful only if there is an
> error:
>
> ls -al /non/existant/directory>  test.log 2>&1
> * will print "No such file or directory" on screen, leaving test.log empty
>
> ls -al /non/existant/directory>  test.log
> * will print "No such file or directory" in test.log

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