Merge pull request #106 from fenollp/shellcheck-fixes

Fix most shellcheck warnings/errors

2 files changed, 120 insertions, 120 deletions

diff --git a/bash_completion/kerl b/bash_completion/kerl
index 559d844..76c4ad2 100644
--- a/bash_completion/kerl
+++ b/bash_completion/kerl
@@ -1,3 +1,4 @@
+#!/bin/bash
 # bash_completion for kerl
 
 _kerl()
@@ -14,33 +15,33 @@ _kerl()
             ;;
         build)
             if [ "$COMP_CWORD" -eq 2 ]; then
-                if [ -f "$HOME/.kerl/otp_releases" ]; then
-                    RELEASES=`cat "$HOME/.kerl/otp_releases"`
+                if [ -f "$HOME"/.kerl/otp_releases ]; then
+                    RELEASES=$(cat "$HOME"/.kerl/otp_releases)
                 fi
                 COMPREPLY=( $( compgen -W "git $RELEASES" -- "$cur") )
             else
-                if [ -f "$HOME/.kerl/otp_builds" ]; then
-                    BUILDS=`cat "$HOME/.kerl/otp_builds" | cut -d "," -f 2`
+                if [ -f "$HOME"/.kerl/otp_builds ]; then
+                    BUILDS=$(cut -d ',' -f 2 "$HOME"/.kerl/otp_builds)
                 fi
                 COMPREPLY=( $( compgen -W "$BUILDS" -- "$cur") )
             fi
             ;;
         installation)
-            if [ -f "$HOME/.kerl/otp_installations" ]; then
-                PATHS=`cat "$HOME/.kerl/otp_installations" | cut -d " " -f 2`
+            if [ -f "$HOME"/.kerl/otp_installations ]; then
+                PATHS=$(cut -d ' ' -f 2 "$HOME"/.kerl/otp_installations)
             fi
             COMPREPLY=( $( compgen -W "$PATHS" -- "$cur") )
             ;;
         install)
-            if [ -f "$HOME/.kerl/otp_builds" ]; then
-                BUILDS=`cat "$HOME/.kerl/otp_builds" | cut -d "," -f 2`
+            if [ -f "$HOME"/.kerl/otp_builds ]; then
+                BUILDS=$(cut -d ',' -f 2 "$HOME"/.kerl/otp_builds)
             fi
             COMPREPLY=( $( compgen -W "$BUILDS" -- "$cur") )
             ;;
          deploy)
             if [ "$COMP_CWORD" -eq 3 ]; then
-                if [ -f "$HOME/.kerl/otp_installations" ]; then
-                    PATHS=`cat "$HOME/.kerl/otp_installations" | cut -d " " -f 2`
+                if [ -f "$HOME"/.kerl/otp_installations ]; then
+                    PATHS=$(cut -d ' ' -f 2 "$HOME"/.kerl/otp_installations)
                 fi
             fi
             COMPREPLY=( $( compgen -W "$PATHS" -- "$cur") )
@@ -53,8 +54,8 @@ _kerl()
             ;;
         *)
             if [ "$COMP_CWORD" -eq 3 ]; then
-                if [ -f "$HOME/.kerl/otp_builds" ]; then
-                    BUILDS=`cat "$HOME/.kerl/otp_builds" | cut -d "," -f 2`
+                if [ -f "$HOME"/.kerl/otp_builds ]; then
+                    BUILDS=$(cut -d ',' -f 2 "$HOME"/.kerl/otp_builds)
                 fi
                 if [ -n "$BUILDS" ]; then
                     for b in $BUILDS; do
@@ -69,4 +70,3 @@ _kerl()
     esac
 }
 complete -F _kerl kerl
-
diff --git a/kerl b/kerl
index 6efb372..24cf1cd 100755
--- a/kerl
+++ b/kerl
@@ -23,11 +23,11 @@
 
 ERLANG_DOWNLOAD_URL=http://www.erlang.org/download
 
-KERL_BASE_DIR="$HOME/.kerl"
-KERL_CONFIG="$HOME/.kerlrc"
-KERL_DOWNLOAD_DIR="$KERL_BASE_DIR/archives"
-KERL_BUILD_DIR="$KERL_BASE_DIR/builds"
-KERL_GIT_DIR="$KERL_BASE_DIR/gits"
+KERL_BASE_DIR="$HOME"/.kerl
+KERL_CONFIG="$HOME"/.kerlrc
+KERL_DOWNLOAD_DIR="${KERL_BASE_DIR:?}"/archives
+KERL_BUILD_DIR="${KERL_BASE_DIR:?}"/builds
+KERL_GIT_DIR="${KERL_BASE_DIR:?}"/gits
 if [ -n "$KERL_CONFIGURE_OPTIONS" ]; then
     _KCO="$KERL_CONFIGURE_OPTIONS"
 fi
@@ -56,10 +56,10 @@ KERL_SASL_STARTUP=
 KERL_INSTALL_MANPAGES=
 
 # ensure the base dir exsists
-mkdir -p "$KERL_BASE_DIR"
+mkdir -p "$KERL_BASE_DIR" || exit 1
 
 # source the config file if available
-if [ -f "$KERL_CONFIG" ]; then . "$KERL_CONFIG"; fi
+if [ -f "$KERL_CONFIG" ]; then source "$KERL_CONFIG"; fi
 
 if [ -n "$_KCO" ]; then
     KERL_CONFIGURE_OPTIONS="$_KCO"
@@ -89,7 +89,7 @@ else
     INSTALL_OPT=-sasl
 fi
 
-KERL_SYSTEM=`uname -s`
+KERL_SYSTEM=$(uname -s)
 case "$KERL_SYSTEM" in
     Darwin|FreeBSD|OpenBSD)
         MD5SUM="openssl md5"
@@ -107,7 +107,7 @@ usage()
 {
     echo "kerl: build and install Erlang/OTP"
     echo "usage: $0 <command> [options ...]"
-    echo "\n  <command>       Command to be executed\n"
+    printf "\n  <command>       Command to be executed\n\n"
     echo "Valid commands are:"
     echo "  build    Build specified release or git repository"
     echo "  install  Install the specified release at the given location"
@@ -135,21 +135,21 @@ get_releases()
 update_checksum_file()
 {
     echo "Getting the checksum file from erlang.org..."
-    curl -L $ERLANG_DOWNLOAD_URL/MD5 > "$KERL_DOWNLOAD_DIR/MD5" || exit 1
+    curl -L $ERLANG_DOWNLOAD_URL/MD5 > "$KERL_DOWNLOAD_DIR"/MD5 || exit 1
 }
 
 ensure_checksum_file()
 {
-    if [ ! -f "$KERL_DOWNLOAD_DIR/MD5" ]; then
+    if [ ! -f "$KERL_DOWNLOAD_DIR"/MD5 ]; then
         update_checksum_file
     fi
 }
 
 check_releases()
 {
-    if [ ! -f "$KERL_BASE_DIR/otp_releases" ]; then
+    if [ ! -f "$KERL_BASE_DIR"/otp_releases ]; then
         echo "Getting the available releases from erlang.org..."
-        get_releases > "$KERL_BASE_DIR/otp_releases"
+        get_releases > "$KERL_BASE_DIR"/otp_releases
     fi
 }
 
@@ -169,17 +169,17 @@ lion_support() {
 is_valid_release()
 {
     check_releases
-    for rel in `cat $KERL_BASE_DIR/otp_releases`; do
+    while read -r rel; do
         if [ "$1" = "$rel" ]; then
             return 0
         fi
-    done
+    done < "$KERL_BASE_DIR"/otp_releases
     return 1
 }
 
 assert_valid_release()
 {
-    if ! is_valid_release $1; then
+    if ! is_valid_release "$1"; then
         echo "$1 is not a valid Erlang/OTP release"
         exit 1
     fi
@@ -188,15 +188,15 @@ assert_valid_release()
 
 get_release_from_name()
 {
-    if [ -f "$KERL_BASE_DIR/otp_builds" ]; then
-        for l in `cat "$KERL_BASE_DIR/otp_builds"`; do
-            rel=`echo $l | cut -d "," -f 1`
-            name=`echo $l | cut -d "," -f 2`
+    if [ -f "$KERL_BASE_DIR"/otp_builds ]; then
+        while read -r l; do
+            rel=$(echo "$l" | cut -d "," -f 1)
+            name=$(echo "$l" | cut -d "," -f 2)
             if [ "$name" = "$1" ]; then
                 echo "$rel"
                 return 0
             fi
-        done
+        done < "$KERL_BASE_DIR"/otp_builds
     fi
     return 1
 }
@@ -204,18 +204,18 @@ get_release_from_name()
 get_newest_valid_release()
 {
     check_releases
-    for rel in `cat $KERL_BASE_DIR/otp_releases | tail -1`; do
+    while read -r rel; do
         if [ ! -z "$rel" ]; then
             echo "$rel"
             return 0
         fi
-    done
+    done < "$KERL_BASE_DIR"/otp_releases | tail -1
     return 1
 }
 
 is_valid_installation()
 {
-    if [ -f "$1/activate" ]; then
+    if [ -f "$1"/activate ]; then
         return 0
     fi
     return 1
@@ -223,7 +223,7 @@ is_valid_installation()
 
 assert_valid_installation()
 {
-    if ! is_valid_installation $1; then
+    if ! is_valid_installation "$1"; then
         echo "$1 is not a kerl-managed Erlang/OTP installation"
         exit 1
     fi
@@ -232,24 +232,24 @@ assert_valid_installation()
 
 assert_build_name_unused()
 {
-    if [ -f "$KERL_BASE_DIR/otp_builds" ]; then
-        for l in `cat "$KERL_BASE_DIR/otp_builds"`; do
-            name=`echo $l | cut -d "," -f 2`
+    if [ -f "$KERL_BASE_DIR"/otp_builds ]; then
+        while read -r l; do
+            name=$(echo "$l" | cut -d "," -f 2)
             if [ "$name" = "$1" ]; then
                 echo "There's already a build named $1"
                 exit 1
             fi
-        done
+        done < "$KERL_BASE_DIR"/otp_builds
     fi
 }
 
 do_git_build()
 {
-    assert_build_name_unused $3
+    assert_build_name_unused "$3"
 
-    GIT=`echo -n "$1" | $MD5SUM | cut -d " " -f $MD5SUM_FIELD`
+    GIT=$(echo -n "$1" | $MD5SUM | cut -d ' ' -f $MD5SUM_FIELD)
     mkdir -p "$KERL_GIT_DIR"
-    cd "$KERL_GIT_DIR"
+    cd "$KERL_GIT_DIR" || exit 1
     echo "Checking Erlang/OTP git repository from $1..."
     if [ ! -d "$GIT" ]; then
         git clone -q --mirror "$1" "$GIT" > /dev/null 2>&1
@@ -258,37 +258,37 @@ do_git_build()
             exit 1
         fi
     fi
-    cd "$GIT"
+    cd "$GIT" || exit 1
     git remote update --prune > /dev/null 2>&1
     if [ $? -ne 0 ]; then
         echo "Error updating remote git repository"
         exit 1
     fi
 
-    rm -Rf "$KERL_BUILD_DIR/$3"
+    rm -Rf "${KERL_BUILD_DIR:?}/$3"
     mkdir -p "$KERL_BUILD_DIR/$3"
-    cd "$KERL_BUILD_DIR/$3"
+    cd "$KERL_BUILD_DIR/$3" || exit 1
     git clone -l "$KERL_GIT_DIR/$GIT" otp_src_git > /dev/null 2>&1
     if [ $? -ne 0 ]; then
         echo "Error cloning local git repository"
         exit 1
     fi
-    cd otp_src_git
-    git checkout $2 > /dev/null 2>&1
+    cd otp_src_git || exit 1
+    git checkout "$2" > /dev/null 2>&1
     if [ $? -ne 0 ]; then
-        git checkout -b $2 $2 > /dev/null 2>&1
+        git checkout -b "$2" "$2" > /dev/null 2>&1
     fi
     if [ $? -ne 0 ]; then
         echo "Couldn't checkout specified version"
-        rm -Rf "$KERL_BUILD_DIR/$3"
+        rm -Rf "${KERL_BUILD_DIR:?}/$3"
         exit 1
     fi
     if [ ! -x otp_build ]; then
         echo "Not a valid Erlang/OTP repository"
-        rm -Rf "$KERL_BUILD_DIR/$3"
+        rm -Rf "${KERL_BUILD_DIR:?}/$3"
         exit 1
     fi
-    LOGFILE="$KERL_BUILD_DIR/$3/otp_build.log"
+    LOGFILE="$KERL_BUILD_DIR/$3"/otp_build.log
     echo "Building Erlang/OTP $3 from git, please wait..."
     ./otp_build autoconf $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1 && \
         ./otp_build configure $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1
@@ -299,7 +299,7 @@ do_git_build()
     if [ -n "$KERL_CONFIGURE_APPLICATIONS" ]; then
         find ./lib -maxdepth 1 -type d -exec touch -f {}/SKIP \;
         for i in $KERL_CONFIGURE_APPLICATIONS; do
-            rm ./lib/$i/SKIP
+            rm ./lib/"$i"/SKIP
             if [ $? -ne 0 ]; then
                 echo "Couldn't prepare '$i' application for building"
                 exit 1
@@ -308,7 +308,7 @@ do_git_build()
     fi
     if [ -n "$KERL_CONFIGURE_DISABLE_APPLICATIONS" ]; then
         for i in $KERL_CONFIGURE_DISABLE_APPLICATIONS; do
-            touch -f ./lib/$i/SKIP
+            touch -f ./lib/"$i"/SKIP
             if [ $? -ne 0 ]; then
                 echo "Couldn't disable '$i' application for building"
                 exit 1
@@ -321,9 +321,9 @@ do_git_build()
         exit 1
     fi
     rm -f "$LOGFILE"
-    ./otp_build release -a "$KERL_BUILD_DIR/$3/release_git" > /dev/null 2>&1
-    cd "$KERL_BUILD_DIR/$3/release_git"
-    ./Install $INSTALL_OPT "$KERL_BUILD_DIR/$3/release_git" > /dev/null 2>&1
+    ./otp_build release -a "$KERL_BUILD_DIR/$3"/release_git > /dev/null 2>&1
+    cd "$KERL_BUILD_DIR/$3"/release_git || exit 1
+    ./Install $INSTALL_OPT "$KERL_BUILD_DIR/$3"/release_git > /dev/null 2>&1
     echo "Erlang/OTP $3 from git has been successfully built"
     list_add builds "git,$3"
 }
@@ -332,11 +332,11 @@ do_build()
 {
     case "$KERL_SYSTEM" in
         Darwin)
-            if [ `gcc --version 2>/dev/null | grep -i llvm | wc -l` = "1" ]; then
-                if lion_support $1; then
+            if [ "$(gcc --version 2>/dev/null | grep -i -c llvm)" = "1" ]; then
+                if lion_support "$1"; then
                     KERL_CONFIGURE_OPTIONS="CFLAGS=-O0 $KERL_CONFIGURE_OPTIONS"
                 else
-                    if [ -x "`which gcc-4.2`" ]; then
+                    if [ -x "$(which gcc-4.2)" ]; then
                         KERL_CONFIGURE_OPTIONS="CC=gcc-4.2 $KERL_CONFIGURE_OPTIONS"
                     else
                         KERL_CONFIGURE_OPTIONS="CC=llvm-gcc-4.2 CFLAGS=-O0 $KERL_CONFIGURE_OPTIONS"
@@ -348,8 +348,8 @@ do_build()
         ;;
     esac
 
-    assert_valid_release $1
-    assert_build_name_unused $2
+    assert_valid_release "$1"
+    assert_build_name_unused "$2"
 
     FILENAME=otp_src_$1.tar.gz
     download "$FILENAME"
@@ -359,12 +359,12 @@ do_build()
         UNTARDIRNAME="$KERL_BUILD_DIR/$2/otp_src_$1-kerluntar-$$"
         rm -rf "$UNTARDIRNAME"
         mkdir -p "$UNTARDIRNAME"
-        (cd "$UNTARDIRNAME" && tar xfz "$KERL_DOWNLOAD_DIR/$FILENAME" && mv * "$KERL_BUILD_DIR/$2/otp_src_$1")
+        (cd "$UNTARDIRNAME" && tar xfz "$KERL_DOWNLOAD_DIR/$FILENAME" && mv ./* "$KERL_BUILD_DIR/$2/otp_src_$1")
         rm -rf "$UNTARDIRNAME"
     fi
     echo "Building Erlang/OTP $1 ($2), please wait..."
     ERL_TOP="$KERL_BUILD_DIR/$2/otp_src_$1"
-    cd "$ERL_TOP"
+    cd "$ERL_TOP" || exit 1
     LOGFILE="$KERL_BUILD_DIR/$2/otp_build_$1.log"
     if [ -n "$KERL_USE_AUTOCONF" ]; then
         ./otp_build autoconf $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1 && \
@@ -381,7 +381,7 @@ do_build()
     if [ -n "$KERL_CONFIGURE_APPLICATIONS" ]; then
         find ./lib -maxdepth 1 -type d -exec touch -f {}/SKIP \;
         for i in $KERL_CONFIGURE_APPLICATIONS; do
-            rm ./lib/$i/SKIP
+            rm ./lib/"$i"/SKIP
             if [ $? -ne 0 ]; then
                 echo "Couldn't prepare '$i' application for building"
                 list_remove builds "$1 $2"
@@ -391,7 +391,7 @@ do_build()
     fi
     if [ -n "$KERL_CONFIGURE_DISABLE_APPLICATIONS" ]; then
         for i in $KERL_CONFIGURE_DISABLE_APPLICATIONS; do
-            touch -f ./lib/$i/SKIP
+            touch -f ./lib/"$i"/SKIP
             if [ $? -ne 0 ]; then
                 echo "Couldn't disable '$i' application for building"
                 exit 1
@@ -406,7 +406,7 @@ do_build()
     fi
     rm -f "$LOGFILE"
     ERL_TOP="$ERL_TOP" ./otp_build release -a "$KERL_BUILD_DIR/$2/release_$1" > /dev/null 2>&1
-    cd "$KERL_BUILD_DIR/$2/release_$1"
+    cd "$KERL_BUILD_DIR/$2/release_$1" || exit 1
     ./Install $INSTALL_OPT "$KERL_BUILD_DIR/$2/release_$1" > /dev/null 2>&1
     echo "Erlang/OTP $1 ($2) has been successfully built"
     list_add builds "$1,$2"
@@ -414,7 +414,7 @@ do_build()
 
 do_install()
 {
-    rel=`get_release_from_name $1`
+    rel=$(get_release_from_name "$1")
     if [ $? -ne 0 ]; then
         echo "No build named $1"
         exit 1
@@ -424,10 +424,10 @@ do_install()
         echo "Destination is not a directory"
         exit 1
     fi
-    absdir=`cd "$2" && pwd`
+    absdir=$(cd "$2" && pwd)
     echo "Installing Erlang/OTP $rel ($1) in $absdir..."
     ERL_TOP="$KERL_BUILD_DIR/$1/otp_src_$rel"
-    cd "$ERL_TOP"
+    cd "$ERL_TOP" || exit 1
     ERL_TOP="$ERL_TOP" ./otp_build release -a "$absdir" > /dev/null 2>&1 &&
         cd "$absdir" && ./Install $INSTALL_OPT "$absdir" > /dev/null 2>&1
     if [ $? -ne 0 ]; then
@@ -435,7 +435,7 @@ do_install()
         exit 1
     fi
     list_add installations "$1 $absdir";
-    cat <<ACTIVATE > "$absdir/activate"
+    cat <<ACTIVATE > "$absdir"/activate
 # credits to virtualenv
 kerl_deactivate()
 {
@@ -512,7 +512,7 @@ ACTIVATE
                 tar -C "$absdir/html" -xzf "$KERL_DOWNLOAD_DIR/$FILENAME")
         fi
     else
-        rel=`get_newest_valid_release`
+        rel=$(get_newest_valid_release)
         if [ $? -ne 0 ]; then
             echo "No newest valid release"
             exit 1
@@ -548,18 +548,18 @@ do_deploy()
         echo "No host given"
         exit 1
     fi
-    host=$1
+    host="$1"
 
     assert_valid_installation "$2"
-    rel=`get_name_from_install_path "$2"`
-    path=$2
-    remotepath=$path
+    rel="$(get_name_from_install_path "$2")"
+    path="$2"
+    remotepath="$path"
 
     if [ ! -z "$3" ]; then
-        remotepath=$3
+        remotepath="$3"
     fi
 
-    ssh $KERL_DEPLOY_SSH_OPTIONS $host true > /dev/null 2>&1
+    ssh $KERL_DEPLOY_SSH_OPTIONS "$host" true > /dev/null 2>&1
     if [ $? -ne 0 ]; then
         echo "Couldn't ssh to $host"
         exit 1
@@ -573,13 +573,13 @@ do_deploy()
         exit 1
     fi
 
-    ssh $KERL_DEPLOY_SSH_OPTIONS $host "cd \"$remotepath\" && env ERL_TOP=\`pwd\` ./Install $INSTALL_OPT \`pwd\` > /dev/null 2>&1"
+    ssh $KERL_DEPLOY_SSH_OPTIONS "$host" "cd \"$remotepath\" && env ERL_TOP=\"\`pwd\`\" ./Install $INSTALL_OPT \"\`pwd\`\" > /dev/null 2>&1"
     if [ $? -ne 0 ]; then
         echo "Couldn't install Erlang/OTP $rel to $host ($remotepath)"
         exit 1
     fi
 
-    ssh $KERL_DEPLOY_SSH_OPTIONS $host "cd \"$remotepath\" && sed -i -e \"s#$path#\`pwd\`#g\" activate"
+    ssh $KERL_DEPLOY_SSH_OPTIONS "$host" "cd \"$remotepath\" && sed -i -e \"s#$path#\"\`pwd\`\"#g\" activate"
     if [ $? -ne 0 ]; then
         echo "Couldn't completely install Erlang/OTP $rel to $host ($remotepath)"
         exit 1
@@ -593,8 +593,8 @@ do_deploy()
 
 list_print()
 {
-    if [ -f $KERL_BASE_DIR/otp_$1 ]; then
-        if [ "`cat "$KERL_BASE_DIR/otp_$1" | wc -l`" != "0" ]; then
+    if [ -f "$KERL_BASE_DIR/otp_$1" ]; then
+        if [ "$(wc -l "$KERL_BASE_DIR/otp_$1")" != "0" ]; then
             if [ -z "$2" ]; then
                 cat "$KERL_BASE_DIR/otp_$1"
             else
@@ -609,11 +609,11 @@ list_print()
 list_add()
 {
     if [ -f "$KERL_BASE_DIR/otp_$1" ]; then
-        for l in `cat "$KERL_BASE_DIR/otp_$1"`; do
+        while read -r l; do
             if [ "$l" = "$2" ]; then
                 return 1
             fi
-        done
+        done < "$KERL_BASE_DIR/otp_$1"
         echo "$2" >> "$KERL_BASE_DIR/otp_$1"
     else
         echo "$2" > "$KERL_BASE_DIR/otp_$1"
@@ -630,7 +630,7 @@ list_remove()
 list_has()
 {
     if [ -f "$KERL_BASE_DIR/otp_$1" ]; then
-        grep $2 "$KERL_BASE_DIR/otp_$1" > /dev/null 2>&1 && return 0
+        grep "$2" "$KERL_BASE_DIR/otp_$1" > /dev/null 2>&1 && return 0
     fi
     return 1
 }
@@ -658,25 +658,25 @@ update_usage()
 get_active_path()
 {
     if [ -n "$_KERL_ACTIVE_DIR" ]; then
-        echo $_KERL_ACTIVE_DIR
+        echo "$_KERL_ACTIVE_DIR"
     fi
     return 0
 }
 
 get_name_from_install_path()
 {
-    if [ -f "$KERL_BASE_DIR/otp_installations" ]; then
-        grep -F "$1" "$KERL_BASE_DIR/otp_installations" | cut -d ' ' -f 1
+    if [ -f "$KERL_BASE_DIR"/otp_installations ]; then
+        grep -F "$1" "$KERL_BASE_DIR"/otp_installations | cut -d ' ' -f 1
     fi
     return 0
 }
 
 do_active()
 {
-    ACTIVE_PATH=`get_active_path`
+    ACTIVE_PATH="$(get_active_path)"
     if [ -n "$ACTIVE_PATH" ]; then
         echo "The current active installation is:"
-        echo $ACTIVE_PATH
+        echo "$ACTIVE_PATH"
         return 0
     else
         echo "No Erlang/OTP kerl installation is currently active"
@@ -694,8 +694,8 @@ download()
     fi
     ensure_checksum_file
     echo "Verifying archive checksum..."
-    SUM=`$MD5SUM "$KERL_DOWNLOAD_DIR/$1" | cut -d " " -f $MD5SUM_FIELD`
-    ORIG_SUM=`grep -F "$1" "$KERL_DOWNLOAD_DIR/MD5" | cut -d " " -f 2`
+    SUM="$($MD5SUM "$KERL_DOWNLOAD_DIR/$1" | cut -d ' ' -f $MD5SUM_FIELD)"
+    ORIG_SUM="$(grep -F "$1" "$KERL_DOWNLOAD_DIR"/MD5 | cut -d ' ' -f 2)"
     if [ "$SUM" != "$ORIG_SUM" ]; then
         echo "Checksum error, check the files in $KERL_DOWNLOAD_DIR"
         exit 1
@@ -710,13 +710,13 @@ case "$1" in
                 echo "usage: $0 $1 $2 <git_url> <git_version> <build_name>"
                 exit 1
             fi
-            do_git_build $3 $4 $5
+            do_git_build "$3" "$4" "$5"
         else
             if [ $# -lt 3 ]; then
                 echo "usage: $0 $1 <release> <build_name>"
                 exit 1
             fi
-            do_build $2 $3
+            do_build "$2" "$3"
         fi
         ;;
     install)
@@ -729,7 +729,7 @@ case "$1" in
                 echo "Refusing to install in $HOME, this is a bad idea."
                 exit 1
             else
-                do_install $2 "$3"
+                do_install "$2" "$3"
             fi
         else
             if [ -z "$KERL_DEFAULT_INSTALL_DIR" ]; then
@@ -737,10 +737,10 @@ case "$1" in
                     echo "Refusing to install in $HOME, this is a bad idea."
                     exit 1
                 else
-                    do_install $2 .
+                    do_install "$2" .
                 fi
             else
-                do_install $2 "$KERL_DEFAULT_INSTALL_DIR/$2"
+                do_install "$2" "$KERL_DEFAULT_INSTALL_DIR/$2"
             fi
         fi
         ;;
@@ -750,12 +750,12 @@ case "$1" in
             exit 1
         fi
         if [ $# -eq 4 ]; then
-            do_deploy $2 "$3" "$4"
+            do_deploy "$2" "$3" "$4"
         else
             if [ $# -eq 3 ]; then
-                do_deploy $2 "$3"
+                do_deploy "$2" "$3"
             else
-                do_deploy $2 .
+                do_deploy "$2" '.'
             fi
         fi
         ;;
@@ -766,7 +766,7 @@ case "$1" in
         fi
         case "$2" in
             releases)
-                rm -f "$KERL_BASE_DIR/otp_releases"
+                rm -f "${KERL_BASE_DIR:?}"/otp_releases
                 check_releases
                 echo "The available releases are:"
                 list_print releases spaces
@@ -785,14 +785,14 @@ case "$1" in
         case "$2" in
             releases)
                 check_releases
-                list_print $2 space
-                echo "Run \"$0 update releases\" to update this list from erlang.org"
+                list_print "$2" space
+                echo "Run '$0 update releases' to update this list from erlang.org"
                 ;;
             builds)
-                list_print $2
+                list_print "$2"
                 ;;
             installations)
-                list_print $2
+                list_print "$2"
                 ;;
             *)
                 echo "Cannot list $2"
@@ -808,23 +808,23 @@ case "$1" in
         fi
         case "$2" in
             build)
-                rel=`get_release_from_name $3`
-                if [ -d "$KERL_BUILD_DIR/$3" ]; then
-                    rm -Rf "$KERL_BUILD_DIR/$3"
+                rel="$(get_release_from_name "$3")"
+                if [ -d "${KERL_BUILD_DIR:?}/$3" ]; then
+                    rm -Rf "${KERL_BUILD_DIR:?}/$3"
                 else
                     if [ -z "$rel" ]; then
                       echo "No build named $3"
                       exit 1
                     fi
                 fi
-                list_remove $2s "$rel,$3"
+                list_remove "$2"s "$rel,$3"
                 echo "The $3 build has been deleted"
                 ;;
             installation)
                 assert_valid_installation "$3"
                 rm -Rf "$3"
-                escaped=`echo "$3" | sed $SED_OPT -e 's#/$##' -e 's#\/#\\\/#g'`
-                list_remove $2s "$escaped"
+                escaped="$(echo "$3" | sed $SED_OPT -e 's#/$##' -e 's#\/#\\\/#g')"
+                list_remove "$2"s "$escaped"
                 echo "The installation in $3 has been deleted"
                 ;;
             *)
@@ -854,11 +854,11 @@ case "$1" in
         if [ -n "$2" ]; then
             FMT="$2"
         fi
-        ACTIVE_PATH=`get_active_path`
+        ACTIVE_PATH="$(get_active_path)"
         if [ -n "$ACTIVE_PATH" ]; then
-            ACTIVE_NAME=`get_name_from_install_path "$ACTIVE_PATH"`
+            ACTIVE_NAME="$(get_name_from_install_path "$ACTIVE_PATH")"
             if [ -z "$ACTIVE_NAME" ]; then
-                VALUE="`basename "$ACTIVE_PATH"`*"
+                VALUE="$(basename "$ACTIVE_PATH")*"
             else
                 VALUE="$ACTIVE_NAME"
             fi
@@ -874,14 +874,14 @@ case "$1" in
         case "$2" in
             all)
                 echo "Cleaning up compilation products for ALL builds"
-                rm -rf $KERL_BUILD_DIR/*
-                rm -rf $KERL_DOWNLOAD_DIR/*
-                rm -rf $KERL_GIT_DIR/*
+                rm -rf "${KERL_BUILD_DIR:?}"/*
+                rm -rf "${KERL_DOWNLOAD_DIR:?}"/*
+                rm -rf "${KERL_GIT_DIR:?}"/*
                 echo "Cleaned up all compilation products under $KERL_BUILD_DIR"
                 ;;
             *)
                 echo "Cleaning up compilation products for $3"
-                rm -rf $KERL_BUILD_DIR/$3
+                rm -rf "${KERL_BUILD_DIR:?}/$3"
                 echo "Cleaned up all compilation products under $KERL_BUILD_DIR"
                 ;;
         esac