diff --git a/README.md b/README.md
index 51a9a99..181f47e 100644
--- a/README.md
+++ b/README.md
@@ -42,10 +42,13 @@ default build command as configured in .cqfdrc, use:
 
     $ cqfd
 
-Alternatively, you may want to specify a custom build command to be
+Alternatively, you may want to specify a single custom command to be
 executed from inside the build container.
 
-    $ cqfd run make clean
+    $ cqfd exec make clean
+
+Or custom commands composed with shell grammar:
+
     $ cqfd run "make linux-dirclean && make foobar-dirclean"
 
 When ``cqfd`` is running, the current directory is mounted by Docker
diff --git a/bash-completion b/bash-completion
index 6d64549..da7b429 100644
--- a/bash-completion
+++ b/bash-completion
@@ -55,9 +55,9 @@ _cqfd() {
 
 	local arg=
 	_get_first_arg
-	if [[ "$arg" == run ]]; then
+	if [[ "$arg" =~ ^(exec|run)$ ]]; then
 		for (( i=1; i <= cword; i++ )); do
-			if [[ ${words[i]} == run ]]; then
+			if [[ ${words[i]} =~ ^(exec|run)$ ]]; then
 				if [[ $((i+1)) -eq $cword ]]; then
 					break
 				elif [[ ${words[i+1]} == -c ]]; then
@@ -68,11 +68,15 @@ _cqfd() {
 			fi
 		done
 
-		COMPREPLY=( $(compgen -c -W "-c" -- "$cur") )
+		if [[ "$arg" == exec ]]; then
+			COMPREPLY=( $(compgen -c -- "$cur") )
+		else
+			COMPREPLY=( $(compgen -c -W "-c" -- "$cur") )
+		fi
 		return
-	elif [[ "$arg" == shell ]]; then
+	elif [[ "$arg" =~ ^(shell|sh|ash|dash|bash|ksh|zsh|csh|tcsh|fish)$ ]]; then
 		for (( i=1; i <= cword; i++ )); do
-			if [[ ${words[i]} == shell ]]; then
+			if [[ ${words[i]} == "$arg" ]]; then
 				((i++))
 				break
 			fi
@@ -91,7 +95,8 @@ _cqfd() {
 		return
 	fi
 
-	local cmds="init flavors run release shell version help"
-	COMPREPLY=( $(compgen -W "$cmds $opts" -- "$cur") )
+	local shells="sh ash dash bash ksh zsh csh tcsh fish"
+	local cmds="init flavors exec run release shell version help"
+	COMPREPLY=( $(compgen -W "$shells $cmds $opts" -- "$cur") )
 } &&
 complete -F _cqfd cqfd
diff --git a/cqfd b/cqfd
index 0b85dbb..9c596bd 100755
--- a/cqfd
+++ b/cqfd
@@ -45,6 +45,7 @@ Options:
 
 Commands:
     init                 Initialize project build container.
+    exec cmd [args]      Run argument(s) inside build container.
     flavors              List flavors from config file to stdout.
     run [cmdstring]      Run argument(s) inside build container.
     release [cmdstring]  Run argument(s) and release software.
@@ -388,8 +389,12 @@ test -n "\$failed" &&
 test_su_session_command && has_su_session_command=1
 
 # Add the host's user and group to the container, and adjust ownership.
+if ! shell=\$(command -v $cqfd_shell); then
+	echo "$cqfd_shell: command not found" >&2
+	exit 127
+fi
 groupadd -og $GROUPS -f builders || die "groupadd command failed."
-useradd -s $cqfd_shell -oN -u $UID -g $GROUPS -d "$cqfd_user_home" $cqfd_user \
+useradd -s \$shell -oN -u $UID -g $GROUPS -d "$cqfd_user_home" $cqfd_user \
 	|| die "useradd command failed."
 mkdir -p "$cqfd_user_home" || die "mkdir command failed."
 chown $UID:$GROUPS "$cqfd_user_home" || die "chown command failed."
@@ -565,6 +570,16 @@ while [ $# -gt 0 ]; do
 	-q)
 		quiet=true
 		;;
+	exec)
+		if [ "$#" -lt 2 ]; then
+			die "command exec requires arguments"
+		fi
+		shift
+		config_load $flavor
+		command_string="${@@Q}"
+		docker_run "$command_string"
+		exit
+		;;
 	run|release)
 		if [ "$1" = "release" ]; then
 			has_to_release=true
@@ -589,7 +604,10 @@ while [ $# -gt 0 ]; do
 		has_alternate_command=true
 		break
 		;;
-	shell)
+	sh|ash|dash|bash|ksh|zsh|csh|tcsh|fish|shell)
+		if [ "$1" != "shell" ]; then
+			cqfd_shell="$1"
+		fi
 		shift
 		config_load "$flavor"
 		command_string="$cqfd_shell"
diff --git a/tests/07-cqfd_exec b/tests/07-cqfd_exec
new file mode 100755
index 0000000..030ad53
--- /dev/null
+++ b/tests/07-cqfd_exec
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+#
+# validate the behavior of exec command
+
+set -o pipefail
+
+. "$(dirname "$0")"/jtest.inc "$1"
+cqfd="$TDIR/.cqfd/cqfd"
+
+cd $TDIR/
+
+jtest_prepare "cqfd exec with no argument should fail"
+if ! $cqfd exec; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd exec with argument should succeed"
+if $cqfd exec true; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd exec should return same status"
+if $cqfd exec exit 10;
+   test "$?" -eq 10; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd exec should preserve the arguments"
+if $cqfd exec /bin/sh -c 'printf "0=$0,*=$*,#=$#"' zero one two three \
+       | grep "0=zero,\*=one two three,#=3$"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
diff --git a/tests/08-cqfd_shell b/tests/08-cqfd_shell
index 2ae0758..870d13e 100755
--- a/tests/08-cqfd_shell
+++ b/tests/08-cqfd_shell
@@ -33,9 +33,43 @@ else
 	jtest_result fail
 fi
 
-jtest_prepare "cqfd shell should fail with 127 if \$CQFD_SHELL is not found"
-if CQFD_SHELL=/bin/non-existant-shell $cqfd shell <<<"tty";
-                                      test "$?" -eq 127; then
+jtest_prepare "cqfd shell should fail with 127 and '/bin/non-existant-shell: command not found'"
+if CQFD_SHELL=/bin/non-existant-shell $cqfd shell <<<"tty" \
+	| tee /dev/stderr | grep -q '/bin/non-existant-shell: command not found';
+                                      test "${PIPESTATUS[0]}" -eq 127; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd sh should succeed and use sh"
+if $cqfd sh <<<'printf "$0"' \
+       | tee /dev/stderr | grep -q "^sh$"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd bash should succeed and use bash"
+if $cqfd bash <<<'printf "$0"' \
+       | tee /dev/stderr | grep -q "^bash$"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd dash should succeed and use dash"
+if $cqfd dash <<<'printf "$0"' \
+       | tee /dev/stderr | grep -q "^dash$"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd zsh should fail with 127 and 'zsh: command not found'"
+if $cqfd zsh 2>&1 <<<'printf "$0"' \
+	| tee /dev/stderr | grep -q 'zsh: command not found';
+   test "${PIPESTATUS[0]}" -eq 127; then
 	jtest_result pass
 else
 	jtest_result fail