What does “/dev/null” mean at the end of shell commands

Question

What is the difference between the following commands?

ssh myhostname \"command1; command2;...commandn;\" 2>/dev/null
ssh myhostname \"command1; command2;         


        

Answer 1

2> means "redirect standard-error" to the given file.

/dev/null is the null file. Anything written to it is discarded.

Together they mean "throw away any error messages".

Answer 2

1 is stdout. 2 is stderr.

Then sometimes you find 2>&1, that means redirecting stderr to stdout.

Answer 3

'/dev/null' essentially means "into the void", discarded. The 2 you mention refers to error output, where it should be directed.

Answer 4

2> means sending standard error to something

/dev/null means a bin

Answer 5

1) Pipe everything on standard error to /dev/null (so ignore it and don't display it)

2) Dev null just points to nowhere, pipe anything to that, and it disappears.