Test for executables: replace 'which' with more robust 'command -v'

Instances of:
if [ $(which <command> ]
have been replaced with:
if command -v <command> >/dev/null
which is considered to be more robust in a range of environments.

scripts/build/chroot_archives: line 259:
	if [ "${LB_APT}" = "aptitude" ] && [ ! $(Chroot chroot "which aptitude") ]
has been left untouched because the chroot might require a more complex command
which would need more testing.

manpages/Makefile: line 42:
	@if [ ! -x "$$(which po4a 2>/dev/null)" ]; \
has been left untouched because I am not sufficiently familiar with makefiles.

frontend/lb

@@ -21,7 +21,7 @@ USAGE="lb {clean|config|build}"
 
 case "${1}" in
 	-h|--help)
-		if [ $(which man) ]
+		if command -v man >/dev/null
 		then
 			man lb
 			exit 0
@@ -76,7 +76,7 @@ case "${1}" in
 		then
 			# User has live-build installed in the system
 			SCRIPT=/usr/lib/live/build/"${COMMAND}"
-		elif [ $(which "${COMMAND}") ]
+		elif command -v "${COMMAND}" >/dev/null
 		then
 			# User has live-build commands in path
 			SCRIPT="${COMMAND}"

frontend/live-build

@@ -23,7 +23,7 @@
 
 set -e
 
-if [ $(which man) ]
+if command -v man >/dev/null
 then
 	man live-build
 else

functions/architectures.sh

@@ -50,7 +50,7 @@ Check_architectures ()
 
 Check_crossarchitectures ()
 {
-	if [ $(which dpkg) ]
+	if command -v dpkg >/dev/null
 	then
 		HOST="$(dpkg --print-architecture)"
 	else

functions/defaults.sh

@@ -14,7 +14,7 @@ New_configuration ()
 	## Runtime
 
 	# Image: Architecture
-	if [ $(which dpkg) ]
+	if command -v dpkg >/dev/null
 	then
 		CURRENT_IMAGE_ARCHITECTURE="$(dpkg --print-architecture)"
 	else
@@ -94,7 +94,7 @@ Set_config_defaults ()
 	LB_SYSTEM="${LB_SYSTEM:-live}"
 
 	# Setting mode (currently: debian, progress-linux)
-	if [ $(which lsb_release) ]
+	if command -v lsb_release >/dev/null
 	then
 		_DISTRIBUTOR="$(lsb_release -is | tr "[A-Z]" "[a-z]")"
 
@@ -802,7 +802,7 @@ Check_config_defaults ()
 {
 	case "${LB_BINARY_FILESYSTEM}" in
 		ntfs)
-			if [ ! $(which ntfs-3g) ]
+			if ! command -v ntfs-3g >/dev/null
 			then
 				Echo_error "Using ntfs as the binary filesystem is currently only supported if ntfs-3g is installed on the host system."
 

functions/losetup.sh

@@ -22,7 +22,7 @@ Lodetach ()
 	# Changes to block devices result in uevents which trigger rules which in
 	# turn access the loop device (ex. udisks-part-id, blkid) which can cause
 	# a race condition. We call 'udevadm settle' to help avoid this.
-	if [ $(which udevadm) ]
+	if command -v udevadm >/dev/null
 	then
 		udevadm settle
 	fi

functions/man.sh

@@ -11,7 +11,7 @@
 
 Man ()
 {
-	if [ $(which man) ]
+	if command -v man >/dev/null
 	then
 		man $(basename ${0})
 		exit 0

functions/packages.sh

@@ -81,7 +81,7 @@ Check_installed ()
 			INSTALL_STATUS=1
 		fi
 	else
-		if [ $(which dpkg-query) ]
+		if command -v dpkg-query >/dev/null
 		then
 			if dpkg-query -s "${PACKAGE}" 2> /dev/null | grep -qs "Status: install"
 			then

scripts/build/bootstrap_debootstrap

@@ -21,7 +21,7 @@ USAGE="${PROGRAM} [--force]"
 # Processing arguments and configuration files
 Init_config_data "${@}"
 
-if [ ! $(which debootstrap) ]
+if ! command -v debootstrap >/dev/null
 then
 	Echo_error "debootstrap - command not found"
 	Echo_verbose "debootstrap can be obtained from http://ftp.debian.org/debian/pool/main/d/debootstrap/"

scripts/build/chroot_archives

@@ -238,7 +238,7 @@ case "${1}" in
 				cp -f cache/indices.bootstrap/*Release* chroot/var/lib/apt/lists
 			fi
 
-			if [ "${LB_APT}" = "aptitude" ] && [ ! $(which aptitude) ]
+			if [ "${LB_APT}" = "aptitude" ] && ! command -v aptitude >/dev/null
 			then
 				Chroot chroot "apt-get ${APT_OPTIONS} update"
 				Chroot chroot "apt-get ${APT_OPTIONS} install aptitude"

scripts/build/config

@@ -182,7 +182,7 @@ Local_arguments ()
 		case "${1}" in
 			--dump)
 				# Dump version
-				if [ $(which dpkg-query) ]
+				if command -v dpkg-query >/dev/null
 				then
 					VERSION_DPKG="$(dpkg-query -f='${Version}' --show live-build)"
 				fi

share/bin/Packages

@@ -11,7 +11,7 @@
 
 set -e
 
-if [ ! $(which grep-aptavail) ]
+if ! command -v grep-aptavail >/dev/null
 then
 	echo "E: program grep-aptavail not found!"
 

share/hooks/normal/0400-update-apt-file-cache.hook.chroot

@@ -8,7 +8,7 @@ set -e
 
 . /live-build/config/binary
 
-if [ $(which apt-file) ] && [ "${LB_APT_INDICES}" = "true" ]
+if command -v apt-file >/dev/null && [ "${LB_APT_INDICES}" = "true" ]
 then
 	apt-file update
 fi

share/hooks/normal/0410-update-apt-xapian-index.hook.chroot

@@ -8,7 +8,7 @@ set -e
 # is not allowed to, and (b) it wants to build the index in the background which
 # will be racy in the context of live-build.
 
-if [ $(which update-apt-xapian-index) ]
+if command -v update-apt-xapian-index >/dev/null
 then
 	PYTHONDONTWRITEBYTECODE=1 update-apt-xapian-index --force --quiet
 fi

share/hooks/normal/0430-update-mlocate-database.hook.chroot

@@ -8,7 +8,7 @@ set -e
 # means that if the live system is later installed to a hard disk then less
 # work will be required after installation.
 
-if [ $(which updatedb.mlocate) ]
+if command -v updatedb.mlocate >/dev/null
 then
 	updatedb.mlocate
 fi