keep='-k -k'
                ;;
        --depth=*)
-               shallow_depth="--depth=`expr "z$1" : 'z-[^=]*=\(.*\)'`"
+               shallow_depth="--depth=$(expr "z$1" : 'z-[^=]*=\(.*\)')"
                ;;
        --depth)
                shift
 reflist=$(get_remote_refs_for_fetch "$@")
 if test "$tags"
 then
-       taglist=`IFS='  ' &&
+       taglist=$(IFS=' ' &&
                  echo "$ls_remote_result" |
                  git show-ref --exclude-existing=refs/tags/ |
                  while read sha1 name
                  do
                        echo ".${name}:${name}"
-                 done` || exit
+                 done) || exit
        if test "$#" -gt 1
        then
                # remote URL plus explicit refspecs; we need to merge them.
       http://* | https://* | ftp://*)
          test -n "$shallow_depth" &&
                die "shallow clone with http not supported"
-         proto=`expr "$remote" : '\([^:]*\):'`
+         proto=$(expr "$remote" : '\([^:]*\):')
          if [ -n "$GIT_SSL_NO_VERIFY" ]; then
              curl_extra_args="-k"
          fi
          if [ -n "$GIT_CURL_FTP_NO_EPSV" -o \
-               "`git config --bool http.noEPSV`" = true ]; then
+               "$(git config --bool http.noEPSV)" = true ]; then
              noepsv_opt="--disable-epsv"
          fi