Redirecting output from a function block to a file in Linux

The way you suggest is actually perfectly valid. The Bash manual gives the function declaration syntax as follows (emphasis mine)¹:

Functions are declared using this syntax:

name () compound-command [ redirections ]

or

function name [()] compound-command [ redirections ]

So this would be perfectly valid and replace the contents of outfile with the argument to myfunc:

myfunc() {
    printf '%s\n' "$1"
} > outfile

Or, to append to outfile:

myappendfunc() {
    printf '%s\n' "$1"
} >> outfile

However, even though you can put the name of your target file into a variable and redirect to that, like this:

fname=outfile

myfunc() { printf '%s\n' "$1"; } > "$fname"

I think think it's much clearer to do the redirection where you call the function – just like recommended in other answers. I just wanted to point out that you can have the redirection as part of the function declaration.

---

¹And this is not a bashism: the POSIX Shell spec also allows redirections in the function definition command.

Do the redirection when you are calling the function.

#!/bin/bash
initialize() {
  echo 'initializing'
  ...
}
#call the function with the redirection you want
initialize >> your_file.log

Alternatively, open a subshell in the function and redirect the subshell output:

#!/bin/bash
initialize() {
  (  # opening the subshell
    echo 'initializing'
    ...
  # closing and redirecting the subshell
  ) >> your_file.log
}
# call the function normally
initialize

You can use for exec for shell redirection not sure if it will work for functions

exec > output_file
function initialize {
  ...
}
initialize