Hello,

i have bash script and my question is if i can with peace of mind point any bash command into dev null? ( >/dev/null )

because i cant veriffy there are any errors or it really executed command. respectivelly how i can veriffy it, any advice? thx

That won't redirect errors, since they normally print to stderr, not stdout.
Many commands have a return code $? which you can test to see if the command executed correctly.

You can redirect any command to /dev/null. All it does is discard any output sent.

Redirection is setup by the shell usually - and that means that any executable can have stdin/stdout/stderr redirected to /dev/null. When stdin is redirected, it causes an end of file condition on a read.

This has no effect on any files opened by that executable (which includes shell scripts that may redirect things elsewhere).

As for verify - in what way do you mean by verify? If you mean "show no output" well, verification is no output... If you mean "the command had no error" then it depends on the command. Nearly all commands will exit with a 0 status on success, and non-zero status on failure. User applications might not follow that standard though. If you mean to identify WHAT error occurred, then you are out of luck. Most exit status reflect only that an error occurred (usually when the status is 1), but not what the error was - that is what stderr is used for.

To amplify the answer about stderr and stdout:

stdout = Standard Output = File Descriptor 1
stderr = Standard Error = File Descriptor 2

It is normal to have background processes either log or go to /dev/null if you don't care about logging.

The ">" by itself redirects stdout by default and is equivalent to "1>".
The ">>" redirects stdout but appends (useful for logging) rather than overwriting.

To send BOTH stdout and stderr to the same place you can use a shortcut such as the following that would send stdout to /dev/null then redirect stderro to stdout (which has already been defined as /dev/null):
>/dev/null 2>&1

The 2>&1 says to redirect file descriptor 2 into file descriptor 1 so they both end up in /dev/null.

Note that order is important. You would not do:
2>&1 >/dev/null
as that would send stderr to wherever stdout was BEFORE you told stdout to go to /dev/null

Similarly you could go to a log file:
>/var/log/mylog 2>&1