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

3 files changed, 6 insertions, 6 deletions

diff --git a/scripts/build/bootstrap_debootstrap b/scripts/build/bootstrap_debootstrap
index b4008de8a..9370c3986 100755
--- a/scripts/build/bootstrap_debootstrap
+++ b/scripts/build/bootstrap_debootstrap
@@ -24,7 +24,7 @@ Arguments "${@}"
 Read_conffiles config/all config/common config/bootstrap config/chroot config/binary config/source
 Set_defaults
 
-if [ ! -x "$(which debootstrap 2>/dev/null)" ]
+if [ ! $(which debootstrap) ]
 then
 	Echo_error "debootstrap - command not found"
 	Echo_verbose "debootstrap can be obtained from http://ftp.debian.org/debian/pool/main/d/debootstrap/"
@@ -76,7 +76,7 @@ then
 	DEBOOTSTRAP_OPTIONS="${DEBOOTSTRAP_OPTIONS} --no-check-gpg"
 fi
 
-if [ -x "/usr/sbin/debootstrap" ]
+if [ $(which debootstrap) ]
 then
 	if [ "${LB_CACHE_PACKAGES}" = "true" ]
 	then
@@ -126,6 +126,6 @@ then
 	# Creating stage file
 	Create_stagefile .build/bootstrap
 else
-	Echo_error "Can't process file /usr/bin/debootstrap (FIXME)"
+	Echo_error "Can't find program debootstrap (FIXME)"
 	exit 1
 fi
diff --git a/scripts/build/chroot_archives b/scripts/build/chroot_archives
index 472b76785..f1166ae40 100755
--- a/scripts/build/chroot_archives
+++ b/scripts/build/chroot_archives
@@ -242,7 +242,7 @@ case "${1}" in
 				cp -f cache/indices.bootstrap/*Release* chroot/var/lib/apt/lists
 			fi
 
-			if [ "${LB_APT}" = "aptitude" ] && [ ! -x /usr/bin/aptitude ]
+			if [ "${LB_APT}" = "aptitude" ] && [ ! $(which aptitude) ]
 			then
 				Chroot chroot "apt-get ${APT_OPTIONS} update"
 				Chroot chroot "apt-get ${APT_OPTIONS} install aptitude"
@@ -260,7 +260,7 @@ case "${1}" in
 			fi
 
 			# Installing aptitude
-			if [ "${LB_APT}" = "aptitude" ] && [ ! -x /chroot/usr/bin/aptitude ]
+			if [ "${LB_APT}" = "aptitude" ] && [ ! $(Chroot chroot "which aptitude") ]
 			then
 				Chroot chroot "apt-get ${APT_OPTIONS} update"
 				Chroot chroot "apt-get ${APT_OPTIONS} install aptitude"
diff --git a/scripts/build/config b/scripts/build/config
index aa275c6b9..e974bc73e 100755
--- a/scripts/build/config
+++ b/scripts/build/config
@@ -178,7 +178,7 @@ Local_arguments ()
 		case "${1}" in
 			--dump)
 				# Dump version
-				if [ -x "$(which dpkg-query 2>/dev/null)" ]
+				if [ $(which dpkg-query) ]
 				then
 					VERSION_DPKG="$(dpkg-query -f='${Version}' --show live-build)"
 				fi