Linux file descriptor - getting current redirection stdout file?

Question

I'm trying to get the current stdout redirection, and having some trouble. I have a script that is always run with stdout redirection ie: ``` myscript.sh > /tmp/output.log ``` In myscript.sh, I need to find out what file it is being output to. I'm trying this currently (not working): ``` logfile=$(readlink -f /proc/self/fd/1) ``` That's outputting logfile = /tmp/sflq.r3f, for instance. I need to instead find that it's going to /tmp/output.log Is this even possible? I'm using korn shell if it matters... Thanks!

Accepted Answer

`$()` uses a pipe (or as it appears for ksh -- a tempfile which ksh appears to use to emulate what usually is a pipe in other shells) to capture the output of readlink.

Inside `$()`, the stdout is that pipe (or tempfile in ksh's case).

You can get around this interposed stdout file with something like:

```
{ logfile=$(readlink -f /proc/self/fd/3); }  3>&1
# my ksh 93 needs the { ;} -- dash, and zsh don't 
echo "The logfile is: $logfile"
```

Now:

```
./myscript.sh > /tmp/output.log
echo OUTPUT.LOG
cat /tmp/output.log
```

should give you:

```
OUTPUT.LOG
The logfile is: /tmp/output.log
```

Another option is to think of a way avoid the variable altogether:

```
echo -n "The logfile is: "
readlink -f /proc/self/fd/1 #goes straight to stdout so no need to capture
```

Linux file descriptor - getting current redirection stdout file?

Solution

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