Is any argument after a redirection ignored, or does it have any unintended consequences?
I was surprised to find that a typo I made in my bash script made absolutely no difference because it was specified after a redirect. E.g. I expected it to complain about something like this
./foo.sh > foo2.log whoops I made a typo
But it doesn’t throw any errors. I have to add a semi colon to actually get it to run as a command and error, something like
./foo.sh > foo2.log; whoops I made a typo
What surprised me even more, is that linux hasn’t given up after the redirect e.g.
./foo.sh > foo2.log whoops I made a typo > command_is_still_going.log
is absolutely fine and command_is_still_going.log is still created
Is the ‘whoops I made a typo’ argument completely ignored, or does it result in some unwanted behaviour? Since I tend to use this a lot.
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Answer
Redirections are parsed and handled, then removed from the command-line. The remaining command-line is then executed. In other words, redirections can appear anywhere in the command-line. As a point of style you should put them at the end.
These are equivalent:
./foo.sh > foo2.log whoops I made a typo ./foo.sh whoops I made a typo > foo2.log
If foo.sh ignores its arguments then “whoops I made a typo” has no effect.
Similarly, these are the same:
./foo.sh > foo2.log whoops I made a typo > command_is_still_going.log ./foo.sh whoops I made a typo > foo2.log > command_is_still_going.log
These are two separate commands:
./foo.sh > foo2.log; whoops I made a typo ./foo.sh > foo2.log whoops I made a typo