fix: check if it is a Real terminal, not just if it is a terminal

This will stop printing stuff to dumb terminals that they don't support.

I've overall audited usage of isatty and replaced the ones with intent
to mean "is a Real terminal" with checking for that. I've also caught a
case of carelessly assuming "is a tty" means "should be colour" in
nix-env.

Change-Id: I6d83725d9a2d932ac94ff2294f92c0a1100d23c9

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index a407c647f..018e34509 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -5,9 +5,9 @@
 #include "signals.hh"
 #include "loggers.hh"
 #include "current-process.hh"
+#include "terminal.hh"
 
 #include <algorithm>
-#include <cctype>
 #include <exception>
 #include <iostream>
 
@@ -347,7 +347,7 @@ int handleExceptions(const std::string & programName, std::function<void()> fun)
 
 RunPager::RunPager()
 {
-    if (!isatty(STDOUT_FILENO)) return;
+    if (!isOutputARealTerminal(StandardOutputStream::Stdout)) return;
     char * pager = getenv("NIX_PAGER");
     if (!pager) pager = getenv("PAGER");
     if (pager && ((std::string) pager == "" || (std::string) pager == "cat")) return;