fix consistency in binary execution and existance checking

 - prefer using `which` over hard coded paths
 - it is redundant to check that the bin pointed to the return of
   `which` exists and is executable, `which` already gives us
   assurance of that if it returns true!
 - the redirection of output (`2>/dev/null`) seems to be
   unnecessary from my testing.

the instances relatnig to fdisk and losetup in functions/defaults.sh have
been left as they are since they get executed by `lb config` which can run
without sudo elevation unlike `lb build` and in that case `which` would
fail to find these binaries resulting in error.

this also fixes a bug showing an error for missing debootstrap - this tool
requires sudo privileges to run and thus is not found via a none elevated
which search.

Gbp-Dch: Short
Closes: #952927

1 files changed, 1 insertions, 1 deletions

diff --git a/functions/man.sh b/functions/man.sh
index 11366b7b4..7896f5a9c 100755
--- a/functions/man.sh
+++ b/functions/man.sh
@@ -10,7 +10,7 @@
 
 Man ()
 {
-	if [ -x "$(which man 2>/dev/null)" ]
+	if [ $(which man) ]
 	then
 		man $(basename ${0})
 		exit 0