Fix Shellcheck SC2006: Use $(...) notation

Use $(...) notation instead of legacy backticked `...`.

https://github.com/koalaman/shellcheck/wiki/SC2006

Signed-off-by: Dan Callahan <danc@element.io>

.ci/scripts/test_export_data_command.sh

@@ -3,7 +3,7 @@
 # Test for the export-data admin command against sqlite and postgres
 
 set -xe
-cd "`dirname "$0"`/../.."
+cd "$(dirname "$0")/../.."
 
 echo "--- Install dependencies"
 

.ci/scripts/test_synapse_port_db.sh

@@ -7,7 +7,7 @@
 
 
 set -xe
-cd "`dirname "$0"`/../.."
+cd "$(dirname "$0")/../.."
 
 echo "--- Install dependencies"
 

debian/build_virtualenv

@@ -15,7 +15,7 @@ export DH_VIRTUALENV_INSTALL_ROOT=/opt/venvs
 # python won't look in the right directory. At least this way, the error will
 # be a *bit* more obvious.
 #
-SNAKE=`readlink -e /usr/bin/python3`
+SNAKE=$(readlink -e /usr/bin/python3)
 
 # try to set the CFLAGS so any compiled C extensions are compiled with the most
 # generic as possible x64 instructions, so that compiling it on a new Intel chip
@@ -24,7 +24,7 @@ SNAKE=`readlink -e /usr/bin/python3`
 # TODO: add similar things for non-amd64, or figure out a more generic way to
 # do this.
 
-case `dpkg-architecture -q DEB_HOST_ARCH` in
+case $(dpkg-architecture -q DEB_HOST_ARCH) in
     amd64)
         export CFLAGS=-march=x86-64
         ;;
@@ -56,7 +56,7 @@ case "$DEB_BUILD_OPTIONS" in
     *)
         # Copy tests to a temporary directory so that we can put them on the
         # PYTHONPATH without putting the uninstalled synapse on the pythonpath.
-        tmpdir=`mktemp -d`
+        tmpdir=$(mktemp -d)
         trap 'rm -r $tmpdir' EXIT
 
         cp -r tests "$tmpdir"
@@ -98,7 +98,7 @@ esac
         --output-file="${PACKAGE_BUILD_DIR}/etc/matrix-synapse/log.yaml"
 
 # add a dependency on the right version of python to substvars.
-PYPKG=`basename "$SNAKE"`
+PYPKG=$(basename "$SNAKE")
 echo "synapse:pydepends=$PYPKG" >> debian/matrix-synapse-py3.substvars
 
 

debian/test/provision.sh

@@ -10,7 +10,7 @@ set -e
 apt-get update
 apt-get install -y lsb-release
 
-deb=`find /debs -name "matrix-synapse-py3_*+$(lsb_release -cs)*.deb" | sort | tail -n1`
+deb=$(find /debs -name "matrix-synapse-py3_*+$(lsb_release -cs)*.deb" | sort | tail -n1)
 
 debconf-set-selections <<EOF
 matrix-synapse matrix-synapse/report-stats boolean false

docker/build_debian.sh

@@ -5,7 +5,7 @@
 set -ex
 
 # Get the codename from distro env
-DIST=`cut -d ':' -f2 <<< "${distro:?}"`
+DIST=$(cut -d ':' -f2 <<< "${distro:?}")
 
 # we get a read-only copy of the source: make a writeable copy
 cp -aT /synapse/source /synapse/build
@@ -17,7 +17,7 @@ cd /synapse/build
 # Section to determine which "component" it should go into (see
 # https://manpages.debian.org/stretch/reprepro/reprepro.1.en.html#GUESSING)
 
-DEB_VERSION=`dpkg-parsechangelog -SVersion`
+DEB_VERSION=$(dpkg-parsechangelog -SVersion)
 case $DEB_VERSION in
     *~rc*|*~a*|*~b*|*~c*)
         sed -ie '/^Section:/c\Section: prerelease' debian/control

scripts-dev/check-newsfragment

@@ -42,9 +42,9 @@ echo "--------------------------"
 echo
 
 matched=0
-for f in `git diff --name-only FETCH_HEAD... -- changelog.d`; do
+for f in $(git diff --name-only FETCH_HEAD... -- changelog.d); do
     # check that any modified newsfiles on this branch end with a full stop.
-    lastchar=`tr -d '\n' < "$f" | tail -c 1`
+    lastchar=$(tr -d '\n' < "$f" | tail -c 1)
     if [ "$lastchar" != '.' ] && [ "$lastchar" != '!' ]; then
         echo -e "\e[31mERROR: newsfragment $f does not end with a '.' or '!'\e[39m" >&2
         echo -e "$CONTRIBUTING_GUIDE_TEXT" >&2

scripts-dev/check_line_terminators.sh

@@ -25,7 +25,7 @@
 # terminators are found, 0 otherwise.
 
 # cd to the root of the repository
-cd "`dirname "$0"`/.." || exit
+cd "$(dirname "$0")/.." || exit
 
 # Find and print files with non-unix line terminators
 if find . -path './.git/*' -prune -o -type f -print0 | xargs -0 grep -I -l $'\r$'; then

scripts-dev/config-lint.sh

@@ -3,7 +3,7 @@
 # Exits with 0 if there are no problems, or another code otherwise.
 
 # cd to the root of the repository
-cd "`dirname "$0"`/.." || exit
+cd "$(dirname "$0")/.." || exit
 
 # Restore backup of sample config upon script exit
 trap "mv docs/sample_config.yaml.bak docs/sample_config.yaml" EXIT

scripts-dev/generate_sample_config

@@ -4,7 +4,7 @@
 
 set -e
 
-cd "`dirname "$0"`/.."
+cd "$(dirname "$0")/.."
 
 SAMPLE_CONFIG="docs/sample_config.yaml"
 SAMPLE_LOG_CONFIG="docs/sample_log_config.yaml"

scripts-dev/next_github_number.sh

@@ -4,6 +4,6 @@ set -e
 
 # Fetch the current GitHub issue number, add one to it -- presto! The likely
 # next PR number.
-CURRENT_NUMBER=`curl -s "https://api.github.com/repos/matrix-org/synapse/issues?state=all&per_page=1" | jq -r ".[0].number"`
+CURRENT_NUMBER=$(curl -s "https://api.github.com/repos/matrix-org/synapse/issues?state=all&per_page=1" | jq -r ".[0].number")
 CURRENT_NUMBER=$((CURRENT_NUMBER+1))
 echo $CURRENT_NUMBER