pager: do not dup2 stderr if it is already redirected

An earlier commit 61b8050 (sending errors to stdout under $PAGER,
2008-02-16) avoided losing the error messages that are sent to the
standard error when $PAGER is in effect by dup2'ing fd 2 to the pager.
his way, showing a tag object that points to a bad object:

$ git show tag-foo

would give the error message to the pager.  However, it was not quite
right if the user did:

$ git show 2>error.log tag-foo

i.e. use the pager but store the errors in a separate file.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/pager.c b/pager.c
index 6b5c9e44b4ded338ddb344ae454d83a685b7569a..0b7e55f476ac17609d88821e78bd89a511f4b3aa 100644 (file)
--- a/pager.c
+++ b/pager.c
@@ -102,7 +102,8 @@ void setup_pager(void)
 
        /* original process continues, but writes to the pipe */
        dup2(pager_process.in, 1);
 
        /* original process continues, but writes to the pipe */
        dup2(pager_process.in, 1);

-       dup2(pager_process.in, 2);
+       if (isatty(2))
+               dup2(pager_process.in, 2);

        close(pager_process.in);
 
        /* this makes sure that the parent terminates after the pager */
        close(pager_process.in);
 
        /* this makes sure that the parent terminates after the pager */