Need a way to temporarily redirect STDOUT

Question

I know how to redirect output in Linux. Thing is, I have alot of output in my bash script and I don't want to type something like

echo $foo >> bar

over and over again. I would much rather do something like:

hey, bash, for the time being put all your STDOUT in "bar"
echo $foo
.
.
OK, bash, you can go back to regular STDOUT now

I tried opening FD 1 as a file:

exec 1>bar

but couldn't get STDOUT back to normal when I was done. Closing the file

exec 1>&-

gave me errors that I couldn't get around.

Any way to do this? Thanks!

Answer 1

You have to first save stdout (by linking it on fd #4 for instance)

exec 4<&1

Redirect stdout

exec 1>bar

And restore saved stdout

exec 1<&4

Answer 2

There are likely several ways to do what you want, but probably the easiest would be a subshell or command group:

( some
  commands
  you
  want
  to
  redirect ) >> logfile

The ( ... ) construct is a subshell; using { ... } is slightly lighter weight as it's just a group of commands. Which to prefer would depend on whether you want variables assigned inside the group to persist afterwards, primarily, although there are a couple other differences as well...