script: Enable SC2006 rule for Gitian scripts

(cherry picked from commit bitcoin/bitcoin@577682d9e8)

contrib/gitian-descriptors/gitian-linux.yml

@@ -47,7 +47,7 @@ script: |
   export GZIP="-9n"
   export TAR_OPTIONS="--mtime="$REFERENCE_DATE\\\ $REFERENCE_TIME""
   export TZ="UTC"
-  export BUILD_DIR=`pwd`
+  export BUILD_DIR=$(pwd)
   mkdir -p ${WRAP_DIR}
   if test -n "$GBUILD_CACHE_ENABLED"; then
     export SOURCES_PATH=${GBUILD_COMMON_CACHE}
@@ -86,7 +86,7 @@ script: |
   create_per-host_faketime_wrappers "2000-01-01 12:00:00"
 
   cd zcash
-  BASEPREFIX=`pwd`/depends
+  BASEPREFIX=$(pwd)/depends
   # Build dependencies for each host
   for i in $HOSTS; do
     make ${MAKEOPTS} -C ${BASEPREFIX} HOST="${i}"
@@ -99,10 +99,10 @@ script: |
   # Create the release tarball using (arbitrarily) the first host
   export GIT_DIR="$PWD/.git"
   ./autogen.sh
-  CONFIG_SITE=${BASEPREFIX}/`echo "${HOSTS}" | awk '{print $1;}'`/share/config.site ./configure --prefix=/
+  CONFIG_SITE=${BASEPREFIX}/$(echo "${HOSTS}" | awk '{print $1;}')/share/config.site ./configure --prefix=/
   make dist
-  SOURCEDIST=`echo zcash-*.tar.gz`
-  DISTNAME=`echo ${SOURCEDIST} | sed 's/.tar.*//'`
+  SOURCEDIST=$(echo zcash-*.tar.gz)
+  DISTNAME=$(echo ${SOURCEDIST} | sed 's/.tar.*//')
   # Correct tar file order
   mkdir -p temp
   pushd temp
@@ -116,7 +116,7 @@ script: |
     export PATH=${BASEPREFIX}/${i}/native/bin:${ORIGPATH}
     mkdir -p distsrc-${i}
     cd distsrc-${i}
-    INSTALLPATH=`pwd`/installed/${DISTNAME}
+    INSTALLPATH=$(pwd)/installed/${DISTNAME}
     mkdir -p ${INSTALLPATH}
     tar --strip-components=1 -xf ../$SOURCEDIST
 

contrib/gitian-descriptors/gitian-osx-signer.yml

@@ -15,7 +15,7 @@ files:
 script: |
   WRAP_DIR=$HOME/wrapped
   mkdir -p ${WRAP_DIR}
-  export PATH=`pwd`:$PATH
+  export PATH=$(pwd):$PATH
   FAKETIME_PROGS="dmg genisoimage"
 
   # Create global faketime wrappers

contrib/gitian-descriptors/gitian-osx.yml

@@ -36,7 +36,7 @@ script: |
   export GZIP="-9n"
   export TAR_OPTIONS="--mtime="$REFERENCE_DATE\\\ $REFERENCE_TIME""
   export TZ="UTC"
-  export BUILD_DIR=`pwd`
+  export BUILD_DIR=$(pwd)
   mkdir -p ${WRAP_DIR}
   if test -n "$GBUILD_CACHE_ENABLED"; then
     export SOURCES_PATH=${GBUILD_COMMON_CACHE}
@@ -77,7 +77,7 @@ script: |
   create_per-host_faketime_wrappers "2000-01-01 12:00:00"
 
   cd bitcoin
-  BASEPREFIX=`pwd`/depends
+  BASEPREFIX=$(pwd)/depends
 
   mkdir -p ${BASEPREFIX}/SDKs
   tar -C ${BASEPREFIX}/SDKs -xf ${BUILD_DIR}/Xcode-11.3.1-11C505-extracted-SDK-with-libcxx-headers.tar.gz
@@ -94,10 +94,10 @@ script: |
   # Create the release tarball using (arbitrarily) the first host
   export GIT_DIR="$PWD/.git"
   ./autogen.sh
-  CONFIG_SITE=${BASEPREFIX}/`echo "${HOSTS}" | awk '{print $1;}'`/share/config.site ./configure --prefix=/
+  CONFIG_SITE=${BASEPREFIX}/$(echo "${HOSTS}" | awk '{print $1;}')/share/config.site ./configure --prefix=/
   make dist
-  SOURCEDIST=`echo bitcoin-*.tar.gz`
-  DISTNAME=`echo ${SOURCEDIST} | sed 's/.tar.*//'`
+  SOURCEDIST=$(echo bitcoin-*.tar.gz)
+  DISTNAME=$(echo ${SOURCEDIST} | sed 's/.tar.*//')
 
   # Correct tar file order
   mkdir -p temp
@@ -112,7 +112,7 @@ script: |
     export PATH=${BASEPREFIX}/${i}/native/bin:${ORIGPATH}
     mkdir -p distsrc-${i}
     cd distsrc-${i}
-    INSTALLPATH=`pwd`/installed/${DISTNAME}
+    INSTALLPATH=$(pwd)/installed/${DISTNAME}
     mkdir -p ${INSTALLPATH}
     tar --strip-components=1 -xf ../$SOURCEDIST
 

contrib/gitian-descriptors/gitian-win-signer.yml

@@ -15,7 +15,7 @@ files:
 - "osslsigncode-Backports-to-1.7.1.patch"
 - "bitcoin-win-unsigned.tar.gz"
 script: |
-  BUILD_DIR=`pwd`
+  BUILD_DIR=$(pwd)
   SIGDIR=${BUILD_DIR}/signature/win
   UNSIGNED_DIR=${BUILD_DIR}/unsigned
 
@@ -32,7 +32,7 @@ script: |
   ./configure --without-gsf --without-curl --disable-dependency-tracking
   make
   find ${UNSIGNED_DIR} -name "*-unsigned.exe" | while read i; do
-    INFILE="`basename "${i}"`"
-    OUTFILE="`echo "${INFILE}" | sed s/-unsigned//`"
+    INFILE="$(basename "${i}")"
+    OUTFILE="$(echo "${INFILE}" | sed s/-unsigned//)"
     ./osslsigncode attach-signature -in "${i}" -out "${OUTDIR}/${OUTFILE}" -sigin "${SIGDIR}/${INFILE}.pem"
   done

contrib/gitian-descriptors/gitian-win.yml

@@ -37,7 +37,7 @@ script: |
   export GZIP="-9n"
   export TAR_OPTIONS="--mtime="$REFERENCE_DATE\\\ $REFERENCE_TIME""
   export TZ="UTC"
-  export BUILD_DIR=`pwd`
+  export BUILD_DIR=$(pwd)
   mkdir -p ${WRAP_DIR}
   if test -n "$GBUILD_CACHE_ENABLED"; then
     export SOURCES_PATH=${GBUILD_COMMON_CACHE}
@@ -101,7 +101,7 @@ script: |
   create_per-host_linker_wrapper "2000-01-01 12:00:00"
 
   cd bitcoin
-  BASEPREFIX=`pwd`/depends
+  BASEPREFIX=$(pwd)/depends
   # Build dependencies for each host
   for i in $HOSTS; do
     make ${MAKEOPTS} -C ${BASEPREFIX} HOST="${i}"
@@ -115,11 +115,10 @@ script: |
   # Create the release tarball using (arbitrarily) the first host
   export GIT_DIR="$PWD/.git"
   ./autogen.sh
-  CONFIG_SITE=${BASEPREFIX}/`echo "${HOSTS}" | awk '{print $1;}'`/share/config.site ./configure --prefix=/
+  CONFIG_SITE=${BASEPREFIX}/$(echo "${HOSTS}" | awk '{print $1;}')/share/config.site ./configure --prefix=/
   make dist
-  SOURCEDIST=`echo bitcoin-*.tar.gz`
-  DISTNAME=`echo ${SOURCEDIST} | sed 's/.tar.*//'`
-
+  SOURCEDIST=$(echo bitcoin-*.tar.gz)
+  DISTNAME=$(echo ${SOURCEDIST} | sed 's/.tar.*//')
   # Correct tar file order
   mkdir -p temp
   pushd temp
@@ -135,7 +134,7 @@ script: |
     export PATH=${BASEPREFIX}/${i}/native/bin:${ORIGPATH}
     mkdir -p distsrc-${i}
     cd distsrc-${i}
-    INSTALLPATH=`pwd`/installed/${DISTNAME}
+    INSTALLPATH=$(pwd)/installed/${DISTNAME}
     mkdir -p ${INSTALLPATH}
     tar --strip-components=1 -xf ../$SOURCEDIST
 

test/lint/lint-shell.sh

@@ -25,7 +25,6 @@ disabled=(
 )
 disabled_gitian=(
     SC2001 # See if you can use ${variable//search/replace} instead.
-    SC2006 # Use $(...) notation instead of legacy backticked `...`.
     SC2035 # Use ./*glob* or -- *glob* so names with dashes won't become options.
     SC2043 # This loop will only ever run once for a constant value. Did you perhaps mean to loop over dir/*, $var or $(cmd)?
     SC2094 # Make sure not to read and write the same file in the same pipeline.