linux - Simple tee example -

can please explain why tee works here:

echo "testtext" | tee file1 > file2 

my understanding tee duplicates input , prints 1 screen.

the above example allows output echo sent 2 files, first redirecting second.

i expect 'testtext' printed screen , passed through file1 , landing in file2. similar how text in following example end in file2.

echo "testtext" > file1 > file2 

can explain missing in understanding?

edit

is because writing file , stdout gets redirected?

your description right: tee receives data stdin , writes both file , stdout. when redirect tee's stdout file, there nothing written terminal because data ended inside second file.

is because writing file , stdout gets redirected?

exactly.

what trying done (demonstrating how tee works):

$ echo "testtext" | tee file1 | tee file2 testtext 

but since tee gnu coreutils accepts several output files specified, 1 can just:

$ echo "testtext" | tee file1 file2 testtext 

but idea of passed through file1 , landing in file2 not correct. shell example:

echo "testtext" > file1 > file2 

makes shell open both files file1 , file2 writing truncates them , since stdout can redirected file directly, last redirection effective (as overrides previous ones).