lint: prefer $() instead of ``

Latter is more concise but has several weaknesses,
including undefined behaviors.

Reference: https://www.shellcheck.net/wiki/SC2006

build-deps.sh

@@ -7,7 +7,7 @@ CUDDVER=3.0.0
 SPINVER=6.5.2
 
 cd extern/src/cudd-$CUDDVER
-./configure --prefix=`pwd`/../..
+./configure --prefix="$(pwd)/../.."
 make
 make install
 

get-deps.sh

@@ -14,11 +14,11 @@ then
 fi
 
 if hash sha256sum >/dev/null 2>&1; then
-    FILECHECKSUM=`sha256sum extern/cudd-$CUDDVER.tar.gz| sed 's/ .*//'`
+    FILECHECKSUM=$(sha256sum extern/cudd-$CUDDVER.tar.gz| sed 's/ .*//')
 elif hash shasum >/dev/null 2>&1; then
-    FILECHECKSUM=`shasum -a 256 extern/cudd-$CUDDVER.tar.gz| sed 's/ .*//'`
+    FILECHECKSUM=$(shasum -a 256 extern/cudd-$CUDDVER.tar.gz| sed 's/ .*//')
 else
-    echo "neither `sha256sum` nor `shasum` found in the PATH."
+    echo 'neither `sha256sum` nor `shasum` found in the PATH.'
     rm extern/cudd-$CUDDVER.tar.gz
     exit 1
 fi

get-extra-deps.sh

@@ -15,11 +15,11 @@ then
 fi
 
 if hash sha256sum >/dev/null 2>&1; then
-    FILECHECKSUM=`sha256sum extern/spin${SPINVER}.tar.gz| sed 's/ .*//'`
+    FILECHECKSUM=$(sha256sum extern/spin${SPINVER}.tar.gz| sed 's/ .*//')
 elif hash shasum >/dev/null 2>&1; then
-    FILECHECKSUM=`shasum -a 256 extern/spin${SPINVER}.tar.gz| sed 's/ .*//'`
+    FILECHECKSUM=$(shasum -a 256 extern/spin${SPINVER}.tar.gz| sed 's/ .*//')
 else
-    echo "neither `sha256sum` nor `shasum` found in the PATH."
+    echo 'neither `sha256sum` nor `shasum` found in the PATH.'
     rm extern/spin${SPINVER}.tar.gz
     exit 1
 fi

tests/test-cli.sh

@@ -13,7 +13,7 @@ if test -z $VERBOSE; then
 fi
 
 
-export PATH=`pwd`/${BUILD_ROOT}:$PATH
+export PATH="$(pwd)/${BUILD_ROOT}:$PATH"
 
 if test $VERBOSE -eq 1; then
     echo '\nChecking for detection of flawed command-line usage...'
@@ -72,15 +72,15 @@ done
 if test $VERBOSE -eq 1; then
    echo '\nParsing version message from `gr1c -V`...'
 fi
-VERSION_LINE=`gr1c -V | head -1`
+VERSION_LINE=$(gr1c -V | head -1)
 echo $VERSION_LINE | grep dev0 > /dev/null 2>&1
 if [ $? -ne 0 ]; then
-    VERSION=`echo ${VERSION_LINE} | cut -d ' ' -f2`
-    VERSION_SPLIT=`echo ${VERSION} | sed 's/\./ /g'`
+    VERSION=$(echo ${VERSION_LINE} | cut -d ' ' -f2)
+    VERSION_SPLIT=$(echo ${VERSION} | sed 's/\./ /g')
     if test $VERBOSE -eq 1; then
         echo 'Found version:' ${VERSION}
     fi
-    if [ `echo ${VERSION_SPLIT} | wc -w` -ne 3 ]; then
+    if [ $(echo ${VERSION_SPLIT} | wc -w) -ne 3 ]; then
         echo $PREFACE 'detected version does not have 3 component numbers'
         echo
         exit 1
@@ -102,7 +102,7 @@ fi
 if test $VERBOSE -eq 1; then
     echo '\nComparing `gr1c help` and `gr1c -h`...'
 fi
-TMPFILE=`$MKTEMP`
+TMPFILE=$($MKTEMP)
 gr1c help > $TMPFILE
 if ! (gr1c -h | diff $TMPFILE -); then
     echo $PREFACE 'Outputs of `gr1c help` and gr1c -h` do not match'
@@ -113,7 +113,7 @@ fi
 if test $VERBOSE -eq 1; then
     echo '\nComparing `gr1c --help` and `gr1c -h`...'
 fi
-TMPFILE=`$MKTEMP`
+TMPFILE=$($MKTEMP)
 gr1c --help > $TMPFILE
 if ! (gr1c -h | diff $TMPFILE -); then
     echo $PREFACE 'Outputs of `gr1c --help` and gr1c -h` do not match'

tests/test-gr1c.sh

@@ -27,7 +27,7 @@ UNREALIZABLE_REFSPECS="trivial_un.spc"
 if test $VERBOSE -eq 1; then
     echo "\nChecking specifications that should be realizable..."
 fi
-for k in `echo $REFSPECS`; do
+for k in $(echo $REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\t gr1c -r $TESTDIR/specs/$k"
     fi
@@ -40,7 +40,7 @@ done
 if test $VERBOSE -eq 1; then
     echo "\nChecking specifications that should be unrealizable..."
 fi
-for k in `echo $UNREALIZABLE_REFSPECS`; do
+for k in $(echo $UNREALIZABLE_REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\t gr1c -r $TESTDIR/specs/$k"
     fi
@@ -70,7 +70,7 @@ REFSPECS="trivial_2var.spc free_counter.spc count_onestep.spc trivial_mustblock.
 if test $VERBOSE -eq 1; then
     echo "\nPerforming regression tests for vanilla GR(1) synthesis..."
 fi
-for k in `echo $REFSPECS`; do
+for k in $(echo $REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\tComparing  gr1c -t txt $TESTDIR/specs/$k \n\t\tagainst $TESTDIR/expected_outputs/${k}.listdump.out"
     fi
@@ -133,7 +133,7 @@ REFSPECS="reach_2var.spc reach_2var_mustblock.spc reach_free_counter.spc reach_f
 if test $VERBOSE -eq 1; then
     echo "\nPerforming regression tests for reachability games..."
 fi
-for k in `echo $REFSPECS`; do
+for k in $(echo $REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\tComparing  gr1c-rg -t txt $TESTDIR/specs/$k \n\t\tagainst $TESTDIR/expected_outputs/${k}.listdump.out"
     fi
@@ -152,7 +152,7 @@ REFSPECS="trivial_partwin gridworld_bool"
 if test $VERBOSE -eq 1; then
     echo "\nPerforming regression tests for interaction..."
 fi
-for k in `echo $REFSPECS`; do
+for k in $(echo $REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\tComparing  gr1c -i $TESTDIR/specs/${k}.spc < $TESTDIR/interaction_scripts/${k}_IN.txt \n\t\tagainst $TESTDIR/interaction_scripts/${k}_OUT.txt"
     fi
@@ -169,7 +169,7 @@ done
 if test $VERBOSE -eq 1; then
     echo "\nChecking detection of flawed specification files..."
 fi
-for k in `ls flawed_specs/*.spc`; do
+for k in $(ls flawed_specs/*.spc); do
     if test $VERBOSE -eq 1; then
         echo "\t gr1c -s $k"
     fi
@@ -186,7 +186,7 @@ done
 if test $VERBOSE -eq 1; then
     echo "\nChecking detection of flawed reachability game (rg) specification files..."
 fi
-for k in `ls flawed_reach_specs/*.spc`; do
+for k in $(ls flawed_reach_specs/*.spc); do
     if test $VERBOSE -eq 1; then
         echo "\t gr1c-rg -s $k"
     fi

tests/test-grpatch.sh

@@ -22,7 +22,7 @@ REFSPECS="gridworld_2x20_1obs"
 if test $VERBOSE -eq 1; then
     echo "\nPerforming regression tests for patch_localfixpoint()..."
 fi
-for k in `echo $REFSPECS`; do
+for k in $(echo $REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\tComparing  gr1c -t aut $TESTDIR/specs/patching/${k}.spc \n\t\tagainst $TESTDIR/expected_outputs/patching/${k}.spc.autdump.out"
     fi

tests/test-verification.sh

@@ -23,7 +23,7 @@ if test $VERBOSE -eq 1; then
 fi
 
 REFSPECS="count_onestep.spc empty.spc free_counter.spc gridworld_bool.spc gridworld_env.spc trivial_2var.spc trivial_mustblock.spc"
-for REFSPC in `echo $REFSPECS`; do
+for REFSPC in $(echo $REFSPECS); do
     if test $VERBOSE -eq 1; then
         echo "\nConstructing strategy for ${TESTDIR}/specs/${REFSPC}"
         echo "\tgr1c -t aut ${TESTDIR}/specs/${REFSPC} > ${REFSPC}.aut"
@@ -33,7 +33,7 @@ for REFSPC in `echo $REFSPECS`; do
         echo "\nVerifying it using Spin..."
         echo "\tgr1c-autman -i specs/${REFSPC} ${REFSPC}.aut -P -o ${REFSPC}.aut.pml"
     fi
-    FORMULA=`$BUILD_ROOT/gr1c-autman -i specs/${REFSPC} ${REFSPC}.aut -P -o ${REFSPC}.aut.pml`
+    FORMULA=$($BUILD_ROOT/gr1c-autman -i specs/${REFSPC} ${REFSPC}.aut -P -o ${REFSPC}.aut.pml)
     if test $VERBOSE -eq 1; then
         echo "\tspin -f \"!(${FORMULA})\" >> ${REFSPC}.aut.pml"
     fi
@@ -44,7 +44,7 @@ for REFSPC in `echo $REFSPECS`; do
     fi
     ${SPINEXE} -a ${REFSPC}.aut.pml
     cc -o pan pan.c
-    if test `./pan -a | grep errors| cut -d: -f2` -ne 0; then
+    if test $(./pan -a | grep errors| cut -d: -f2) -ne 0; then
         echo $PREFACE "Strategy does not satisfy specification ${TESTDIR}/specs/${REFSPC}\n"
         exit 1
     fi