diff --git a/Dockerfile b/Dockerfile
index 6cc5f54..d866ff8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -180,12 +180,16 @@ RUN apt update && \
         ca-certificates \
         clang \
         clang-format \
+        colorized-logs `# For help50` \
         coreutils `# For fold` \
         cowsay \
         curl \
         dos2unix \
         dnsutils `# For nslookup` \
+        expect `# For help50` \
+        file `# For help50` \
         fonts-noto-color-emoji `# For render50` \
+        fzf `# For help50` \
         gdb \
         git \
         git-lfs \
@@ -253,7 +257,6 @@ RUN pip3 install --no-cache-dir \
         cs50 \
         Flask \
         Flask-Session \
-        help50 \
         pytest \
         render50 \
         setuptools \
diff --git a/Makefile b/Makefile
index 728d8eb..2d9b392 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ rebuild:
 	docker build --build-arg VCS_REF=$(shell git rev-parse HEAD) --no-cache --tag $(IMAGE) .
 
 run:
-	docker run --env LANG=$(LANG) --env LOCAL_WORKSPACE_FOLDER="$(PWD)" --interactive --publish-all --rm --security-opt seccomp=unconfined --tty --volume "$(PWD)":/mnt --volume /var/run/docker.sock:/var/run/docker-host.sock --workdir /mnt $(IMAGE) bash --login || true
+	docker run --env LANG=$(LANG) --env LOCAL_WORKSPACE_FOLDER="$(PWD)" --env WORKDIR=/mnt --interactive --publish-all --rm --security-opt seccomp=unconfined --tty --volume "$(PWD)":/mnt --volume /var/run/docker.sock:/var/run/docker-host.sock --workdir /mnt cs50/cli bash --login || true
 
 squash: depends
 	docker-squash --tag $(IMAGE) $(IMAGE)
diff --git a/etc/profile.d/cli.sh b/etc/profile.d/cli.sh
index 779b08e..9727517 100644
--- a/etc/profile.d/cli.sh
+++ b/etc/profile.d/cli.sh
@@ -1,5 +1,5 @@
 # If not root
-if [ "$(whoami)" != "root" ]; then
+if [ `id -u` -ne 0 ]; then
 
     # $PATH
     export PATH="/opt/cs50/bin":"/opt/bin":"$PATH"
@@ -60,4 +60,9 @@ if [ "$(whoami)" != "root" ]; then
 
     # Valgrind
     export VALGRIND_OPTS="--memcheck:leak-check=full --memcheck:show-leak-kinds=all --memcheck:track-origins=yes"
+
+    # Start help50 if enabled
+    if help50 is-enabled > /dev/null; then
+        help50 start
+    fi
 fi
diff --git a/etc/profile.d/help50.sh b/etc/profile.d/help50.sh
new file mode 100644
index 0000000..04dca38
--- /dev/null
+++ b/etc/profile.d/help50.sh
@@ -0,0 +1,128 @@
+# If not started
+if [[ -z "$HELP50" ]]; then
+    return
+fi
+
+# Directory with helpers
+HELPERS="/opt/cs50/lib/help50"
+
+# Library
+. /opt/cs50/lib/cli
+
+# Ignore duplicates (but not commands that begin with spaces)
+export HISTCONTROL="ignoredups"
+
+function _help50() {
+
+    # Get exit status of last command
+    local status=$?
+
+    # Get last command line, independent of user's actual history
+    histfile=$(mktemp)
+    HISTFILE=$histfile history -a
+    local argv=$(HISTFILE=$histfile history 1 | cut -c 8-) # Could technically contain multiple commands, separated by ; or &&
+    rm --force $histfile
+    local argv0=$(echo "$argv" | awk '{print $1}') # Assume for simplicity it's just a single command
+
+    # Remove any of these aliases
+    for name in n no y yes; do
+        unalias $name 2> /dev/null
+    done
+
+    # If last command was ./*
+    # touch foo.c && make foo && touch foo.c && ./foo
+    if [[ "$argv" =~ ^\./(.*)$ ]]; then
+        local src="${BASH_REMATCH[1]}.c"
+        local dst="${BASH_REMATCH[1]}"
+        if [[ -f "$src" && $(file --brief --mime-type "$src") == "text/x-c" ]]; then
+            if [[ -x "$dst" && $(file --brief --mime-type "$dst") == "application/x-pie-executable" ]]; then
+                if [[ "$src" -nt "$dst" ]]; then
+                    _helpful "It looks like \`$src\` has changed. Did you mean to run \`make $dst\` again?"
+                fi
+            fi
+        fi
+    fi
+
+    # If last command erred (and is not ctl-c or ctl-z)
+    # https://tldp.org/LDP/abs/html/exitcodes.html
+    if [[ $status -ne 0 && $status -ne 130 && $status -ne 148 ]]; then
+
+        # Read typescript from disk
+        local typescript=$(cat $HELP50)
+
+        # Remove script's own output (if this is user's first command)
+        typescript=$(echo "$typescript" | sed '1{/^Script started on .*/d}')
+
+        # Cap typescript at MIN(1K lines, 1M bytes), else `read` is slow
+        typescript=$(echo "$typescript" | head -n 1024 | cut -b 1-1048576)
+
+        # Remove any line continuations from command line
+        local lines=""
+        while IFS= read -r line || [[ -n "$line" ]]; do
+            if [[ -z $done && $line =~ \\$ ]]; then
+                lines+="${line%\\}"
+            else
+                lines+="$line"$'\n'
+                local done=1
+            fi
+        done <<< "$typescript"
+        typescript="$lines"
+
+        # Remove command line from typescript
+        typescript=$(echo "$typescript" | sed '1d')
+
+        # Remove ANSI characters
+        typescript=$(echo "$typescript" | ansi2txt)
+
+        # Remove control characters
+        # https://superuser.com/a/237154
+        typescript=$(echo "$typescript" | col -bp)
+
+        # Try to get help
+        for helper in $HELPERS/*; do
+            if [[ -f $helper && -x $helper ]]; then
+                local help=$($helper $argv <<< "$typescript")
+                if [[ -n "$help" ]]; then
+                    break
+                fi
+            fi
+        done
+        if [[ -n "$help" ]]; then # If helpful
+            _helpful "$help"
+        elif [[ $status -ne 0 ]]; then # If helpless
+            _helpless "$typescript"
+        fi
+    else
+        _helped
+    fi
+
+    # Truncate typescript
+    truncate -s 0 $HELP50
+}
+
+function _rhetorical() {
+    _alert "That was a rhetorical question. <3"
+}
+
+# Default helpers
+if ! type _helped >/dev/null 2>&1; then
+    function _helped() { :; } # Silent
+fi
+if ! type _helpful >/dev/null 2>&1; then
+    function _helpful() {
+
+        # Intercept accidental invocation of `yes` and `n`, which are actual programs
+        for name in n no y yes; do
+            alias $name=_rhetocial
+        done
+
+        # Output help
+        local output=$(_ansi "$1")
+        _alert "$output"
+    }
+fi
+if ! type _helpless >/dev/null 2>&1; then
+    function _helpless() { :; } # Silent
+fi
+
+export PROMPT_COMMAND=_help50
diff --git a/opt/cs50/bin/help50 b/opt/cs50/bin/help50
new file mode 100755
index 0000000..7b88dc5
--- /dev/null
+++ b/opt/cs50/bin/help50
@@ -0,0 +1,107 @@
+#!/bin/bash
+
+# If root
+if [[ `id -u` -eq 0 ]]; then
+    exit 1
+fi
+
+function _disable() {
+    touch /tmp/help50.lock
+}
+
+function _is-enabled() {
+    if [[ -f /tmp/help50.lock ]]; then
+        echo disabled
+        return 1
+    else
+        echo enabled
+        return 0
+    fi
+}
+
+function _enable() {
+    rm --force /tmp/help50.lock
+}
+
+function _start() {
+
+    # If already helping
+    if [[ -n "$HELP50" ]]; then
+        return 0
+    fi
+
+    # Uniquely identify typescript using PID of parent shell to help
+    local HELP50=/tmp/help50.$PPID
+
+    # Start `script` in background, using ; instead of && for command,
+    # else if user logs out (as via ctl-d) after a non-0 command, bash exits with 127
+    set -o monitor
+    HELP50=$HELP50 script --append --command "bash --login ; exit 1" --flush --quiet --return $HELP50
+    local status=$?
+
+    # No longer helping
+    rm --force $HELP50
+
+    # If `script` was killed, in which case `exit 1` above won't execute
+    if [[ $status -ne 1 ]]; then
+
+        # Without this, prompt ends up below and to right of "Session terminated, killing shell... ...killed."
+        echo -e "\r"
+
+    # Else if `script` exited on its own, as via ctl-d or `logout`
+    else
+
+        # Kill parent shell, since user presumably wants to exit
+        kill -SIGHUP $PPID
+    fi
+}
+
+function _status() {
+    if [[ -n "$HELP50" ]]; then
+        echo started
+        return 0
+    else
+        echo stopped
+        return 1
+    fi
+}
+
+function _stop() {
+
+    # If not helping
+    if [[ -z "$HELP50" ]]; then
+        return 0
+    fi
+
+    # Kill grandparent process (i.e., `script` itself)
+    local ppid=$(ps -o ppid= -p $$) # bash --login
+    local gppid=$(ps -o ppid= -p $ppid) # sh -c
+    local ggppid=$(ps -o ppid= -p $gppid) # script
+    kill -SIGTERM $ggppid
+}
+
+# Parse argument
+case "$1" in
+    disable)
+        _disable
+        ;;
+    enable)
+        _enable
+        ;;
+    is-enabled)
+        _is-enabled
+        ;;
+    start)
+        _start
+        ;;
+    status)
+        _status
+        ;;
+    stop)
+        _stop
+        ;;
+    *)
+        echo "Usage: $0 [disable|enable|is-enabled|start|status|stop]"
+        exit 1
+        ;;
+esac
diff --git a/opt/cs50/bin/http-server b/opt/cs50/bin/http-server
index a0f1c26..ea82a17 100755
--- a/opt/cs50/bin/http-server
+++ b/opt/cs50/bin/http-server
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+. /opt/cs50/lib/cli
+
 # Default options
 a="-a 0.0.0.0"
 c="-c-1"
@@ -9,22 +11,16 @@ port="-p 8080"
 options="--no-dotfiles"
 t="-t0"
 
-# Formatting
-bold=$(tput bold)
-normal=$(tput sgr0)
-
 # Check for app.py or wsgi.py
 if [[ -f app.py ]] || [[ -f wsgi.py ]]; then
-    read -p "Are you sure you want to run ${bold}http-server${normal} and not ${bold}flask${normal}? [y/N] " -r
-    if [[ ! "${REPLY,,}" =~ ^y|yes$ ]]; then
+    if ! _sure "Are you sure you want to run \`http-server\` and not \`flask\`?"; then
         exit 1
     fi
 fi
 
 # Check for path
 if [[ $# -eq 1 ]] && [[ $1 != -* ]] && [[ ! $1 =~ ^\./?$ ]]; then
-    read -p "Are you sure you want to serve ${bold}${1}${normal} and not your current directory? [y/N] " -r
-    if [[ ! "${REPLY,,}" =~ ^y|yes$ ]]; then
+    if ! _sure "Are you sure you want to serve \`${1}\` and not your current directory?"; then
         exit 1
     fi
 fi
diff --git a/opt/cs50/bin/make b/opt/cs50/bin/make
index 4658e3e..1548007 100755
--- a/opt/cs50/bin/make
+++ b/opt/cs50/bin/make
@@ -1,23 +1,18 @@
 #!/bin/bash
 
-# Ensure no targets end with .c
-args=""
-invalid_args=0
-for arg; do
-    case "$arg" in
-        (*.c) arg=${arg%.c}; invalid_args=1;;
-    esac
-    args="$args $arg"
-done
-if [ $invalid_args -eq 1 ]; then
-    echo "Did you mean 'make$args'?"
-    exit 1
-fi
+# If a single target and not an option
+if [[ $# -eq 1 ]] && [[ "$1" != -* ]]; then
+
+    # If target ends with .c or is a directory
+    if [[ "$1" == *?.c || -d "$1" ]]; then
 
-# Run make
-if [[ -d "$1" ]]; then
-    echo "$1 is a directory"
-    exit 1
-else
-    /usr/bin/make -B -s $*
+        # Don't suppress "Nothing to be done" with --silent
+        /usr/bin/make "$1"
+
+        # Else make exits with 0
+        exit 1
+    fi
 fi
+
+# Don't echo recipes
+/usr/bin/make --always-make --silent "$@"
diff --git a/opt/cs50/bin/sqlite3 b/opt/cs50/bin/sqlite3
index 3c1c0e7..b2dd85e 100755
--- a/opt/cs50/bin/sqlite3
+++ b/opt/cs50/bin/sqlite3
@@ -1,8 +1,6 @@
 #!/bin/bash
 
-# Formatting
-bold=$(tput bold)
-normal=$(tput sgr0)
+. /opt/cs50/lib/cli
 
 # If data is coming from stdin (pipe or redirection)
 if [[ -p /dev/stdin || ! -t 0 ]]; then
@@ -12,8 +10,7 @@ fi
 
 # If no command-line argument
 if [[ $# -eq 0 ]]; then
-    read -p "Are you sure you want to run ${bold}sqlite3${normal} without a command-line argument (e.g., the filename of a database)? [y/N] " -r
-    if [[ ! "${REPLY,,}" =~ ^y|yes$ ]]; then
+    if ! _sure "Are you sure you want to run \`sqlite3\` without a command-line argument (e.g., the filename of a database)?"; then
         exit 1
     fi
 
@@ -21,13 +18,11 @@ if [[ $# -eq 0 ]]; then
 elif [[ $# -eq 1 ]] && [[ ! "$1" =~ ^- ]]; then
     if [[ ! -f "$1" ]]; then
         if [[ ! "$1" =~ \.db$ ]]; then
-            read -p "Are you sure you want to create ${bold}$1${normal}? SQLite filenames usually end in ${bold}.db${normal}. [y/N] " -r
-            if [[ ! "${REPLY,,}" =~ ^y|yes$ ]]; then
+            if ! _sure "Are you sure you want to create \`$1\`? SQLite filenames usually end in \`.db\`."; then
                 exit 1
             fi
         else
-            read -p "Are you sure you want to create ${bold}$1${normal}? [y/N] " -r
-            if [[ ! "${REPLY,,}" =~ ^y|yes$ ]]; then
+            if ! _sure "Are you sure you want to create \`$1\`?"; then
                 exit 1
             fi
         fi
diff --git a/opt/cs50/bin/valgrind b/opt/cs50/bin/valgrind
index 60a6429..dd19aa8 100755
--- a/opt/cs50/bin/valgrind
+++ b/opt/cs50/bin/valgrind
@@ -1,12 +1,8 @@
 #!/bin/bash
 
-# Formatting
-bold=$(tput bold)
-normal=$(tput sgr0)
-
 # If run on Python program
 if [[ "$1" == "python" || "$1" == *.py ]]; then
-    echo "Afraid ${bold}valgrind${normal} does not support Python programs!"
+    echo "$(_help "Afraid \`valgrind\` does not support Python programs!")"
     exit 1
 fi
 
diff --git a/opt/cs50/lib/cli b/opt/cs50/lib/cli
new file mode 100644
index 0000000..9db45f2
--- /dev/null
+++ b/opt/cs50/lib/cli
@@ -0,0 +1,78 @@
+function _alert() {
+    echo -e "\033[33m${1}\033[39m" # Yellow
+}
+
+function _ansi() {
+
+    # If command-line arguments
+    if [[ -t 0 ]]; then
+        input="$*"
+
+    # If standard input
+    else
+        input=$(cat)
+    fi
+
+    # Format backticks as bold
+    local bold=$(printf '\033[1m')
+    local normal=$(printf '\033[22m')
+    echo "$input" | sed "s/\`\\([^\`]*\\)\`/${bold}\\1${normal}/g" | _fold
+}
+
+function _find() {
+
+    # Usage
+    if [[ $# -eq 1 ]]; then # Files AND directories
+        local path="$1"
+        local type=""
+    elif [[ $# -eq 3 && "$1" == "-type" && "$2" =~ ^[df]$ ]]; then # Files OR directories
+        local type="$1 $2"
+        local path="$3"
+    else
+        return
+    fi
+
+    # Find $path in descendants of $WORKDIR, excluding hidden directories, most recently modified first
+    paths=$(find "$WORKDIR" -not -path "*/.*" -name "$path" -printf "%T+ %p\n" $type | sort -nr | awk '{print $2}' 2> /dev/null)
+
+    # Count paths
+    local count=$(echo "$paths" | grep -c .)
+
+    # If just one
+    if [[ "$count" -eq 1 ]]; then
+
+        # Resolve absolute path to relative path
+        realpath --relative-to=. "$(dirname "$paths")"
+    fi
+}
+
+function _fold() {
+
+    # If command-line arguments
+    if [[ -t 0 ]]; then
+        input="$*"
+
+    # If standard input
+    else
+        input=$(cat)
+    fi
+
+    # Wrap long lines
+    local cols=$(tput cols)
+    echo "$input" | fold --spaces --width=$cols
+}
+
+function _sure() {
+    if [[ $# -ne 1 ]]; then
+        return 1
+    fi
+    local prompt=$(echo "$1" | _ansi)
+    while true; do
+        read -p "$prompt [y/N] " -r
+        if [[ "${REPLY,,}" =~ ^(y|yes)$ ]]; then
+            return 0
+        else
+            return 1
+        fi
+    done
+}
diff --git a/opt/cs50/lib/help50/bash b/opt/cs50/lib/help50/bash
new file mode 100755
index 0000000..bf00e0b
--- /dev/null
+++ b/opt/cs50/lib/help50/bash
@@ -0,0 +1,114 @@
+#!/bin/bash
+
+output=$(cat)
+
+# touch foo.py && foo.py
+regex="bash: (.*\.py): command not found"
+if [[ "$output" =~ $regex ]]; then
+
+    # If file exists
+    if [[ -f "${BASH_REMATCH[1]}" ]]; then
+        echo "Did you mean to run \`python ${BASH_REMATCH[1]}\`?"
+        exit
+    fi
+fi
+
+# mkdir foo && (foo || 1s || .\foo)
+regex="bash: (.*): command not found"
+if [[ "$output" =~ $regex ]]; then
+
+    # If directory exists
+    if [[ -d "${BASH_REMATCH[1]}" ]]; then
+        echo "Did you mean to run \`cd ${BASH_REMATCH[1]}\`?"
+        exit
+    fi
+
+    # If typo
+    if [[ "${BASH_REMATCH[1]}" == "1s" ]]; then
+        echo "Did you mean to run \`ls\` (which starts with a lowercase L)?"
+        exit
+    fi
+
+    # If uppercase
+    argv0="${BASH_REMATCH[1],,}" # Lowercase it
+    if command -v "$argv0" &> /dev/null; then
+        echo "Did you mean to run \`$argv0\`, in lowercase instead?"
+        exit
+    fi
+
+    # If CS50 command
+    if [[ "${BASH_REMATCH[1]}" =~ ^(check|style|submit)$ && "$2" == "50" ]]; then
+        echo "Did you mean to run \`${BASH_REMATCH[1]}50\`, without a space, instead?"
+        exit
+    fi
+
+    # If backslash instead of forward slash
+    if [[ "${BASH_REMATCH[1]}" =~ ^\.(.*) ]]; then
+        if [[ -f "./${BASH_REMATCH[1]}" ]]; then
+            echo "Did you mean to run \`./${BASH_REMATCH[1]}\`, with a forward slash instead?"
+            exit
+        fi
+    fi
+fi
+
+# mkdir foo && ./foo
+regex="bash: \./([^:]*): Is a directory"
+if [[ "$output" =~ $regex ]]; then
+    echo "Cannot execute a directory. Did you mean to run \`cd ${BASH_REMATCH[1]}\`?"
+    exit
+fi
+
+# touch foo && cd foo
+regex="bash: cd: (.*): Not a directory"
+if [[ "$output" =~ $regex ]]; then
+    file="${BASH_REMATCH[1]}"
+    echo "Looks like you're trying to change directories, but \`$file\` isn't a directory."
+    exit
+fi
+
+# touch foo.c && ./foo.c
+regex="bash: \./((.*)\.c): Permission denied"
+if [[ "$output" =~ $regex ]]; then
+
+    # If file exists
+    if [[ -f "${BASH_REMATCH[1]}" ]]; then
+        echo "Did you mean to run \`make ${BASH_REMATCH[2]}\` and then \`./${BASH_REMATCH[2]}\`?"
+        exit
+    fi
+fi
+
+# touch foo.py && ./foo.py
+regex="bash: \./(.*\.py): Permission denied"
+if [[ "$output" =~ $regex ]]; then
+
+    # If file exists
+    if [[ -f "${BASH_REMATCH[1]}" ]]; then
+        echo "Did you mean to run \`python ${BASH_REMATCH[1]}\`?"
+        exit
+    fi
+fi
+
+# echo "int main(void) {}" > foo && ./foo
+regex="bash: \./([^\.]*): Permission denied"
+if [[ "$output" =~ $regex ]]; then
+    if [[ $(file --brief --mime-type "${BASH_REMATCH[1]}") == "text/x-c" ]]; then
+        echo "Did you mean to give \`"${BASH_REMATCH[1]}"\` a name of \`"${BASH_REMATCH[1]}".c\` (and then compile it with \`make\`) instead?"
+        exit
+    fi
+fi
+
+# touch foo && /.foo
+regex="bash: /\.([^:]*): No such file or directory"
+if [[ "$output" =~ $regex ]]; then
+    if [[ -f "${BASH_REMATCH[1]}" ]]; then
+        echo "Did you mean to run \`./${BASH_REMATCH[1]}\`?"
+        exit
+    fi
+fi
+
+# int main(void) || do {
+regex="bash: syntax error near unexpected token \`.*'"
+if [[ "$output" =~ $regex ]]; then
+    echo "Did you mean to type that in a file instead of your terminal window?"
+    exit
+fi
diff --git a/opt/cs50/lib/help50/cd b/opt/cs50/lib/help50/cd
new file mode 100755
index 0000000..8fa9262
--- /dev/null
+++ b/opt/cs50/lib/help50/cd
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+. /opt/cs50/lib/cli
+
+output=$(cat)
+
+# mkdir -p foo/bar && cd bar
+regex="cd: (.*): No such file or directory"
+if [[ "$output" =~ $regex ]]; then
+
+    # Search recursively for directory
+    dir="${BASH_REMATCH[1]}"
+    parent=$(_find -type d "$dir")
+    echo -n "There isn't a directory called \`$dir\` in your current directory."
+    if [[ ! -z "$parent" ]]; then
+        echo " Did you mean to run \`cd $parent\` first?"
+    else
+        echo
+    fi
+fi
+
+# cd.. || cd.
+regex="bash: cd\.\.?: command not found"
+if [[ "$output" =~ $regex ]]; then
+    echo "Did you mean to run \`cd ..\` instead?"
+    exit
+fi
diff --git a/opt/cs50/lib/help50/clang b/opt/cs50/lib/help50/clang
new file mode 100755
index 0000000..8c7aa69
--- /dev/null
+++ b/opt/cs50/lib/help50/clang
@@ -0,0 +1,14 @@
+#!/bin/bash
+
+output=$(cat)
+
+# touch helpers.c && make helpers
+regex="undefined reference to \`main'"
+if [[ "$output" =~ $regex ]]; then
+    regex="make: \*\*\* \[<builtin>: (.*)\] Error 1"
+    if [[ "$output" =~ $regex ]]; then
+        file="${BASH_REMATCH[1]}.c"
+        echo "Looks like \`$file\` does not have a \`main\` function. Did you mean to \`make\` something else?"
+        exit
+    fi
+fi
diff --git a/opt/cs50/lib/help50/make b/opt/cs50/lib/help50/make
new file mode 100755
index 0000000..db79c38
--- /dev/null
+++ b/opt/cs50/lib/help50/make
@@ -0,0 +1,45 @@
+#!/bin/bash
+
+. /opt/cs50/lib/cli
+
+output=$(cat)
+
+regex="make: Nothing to be done for '(.*)'"
+if [[ "$output" =~ $regex ]]; then
+
+    # If target is a directory
+    if [[ -d "${BASH_REMATCH[1]}" ]]; then
+        echo "Cannot run \`make\` on a directory. Did you mean to run \`cd ${BASH_REMATCH[1]}\` instead?"
+        exit
+    fi
+
+    # If target ends with .c
+    if [[ "${BASH_REMATCH[1]}" == *?.c ]]; then
+        base="${BASH_REMATCH[1]%.c}"
+        if [[ -n "$base" && ! -d "$base" ]]; then
+            echo "Did you mean to run \`make ${base}\` instead?"
+            exit
+        fi
+    fi
+
+fi
+
+regex="make: \*\*\* No rule to make target '(.*)'"
+if [[ "$output" =~ $regex ]]; then
+
+    # If no .c file for target
+    file="${BASH_REMATCH[1]}"
+    [[ "$file" == *.c ]] || file="$file.c"
+    if [[ ! -f "$file" ]]; then
+
+        # Search recursively for .c file
+        dir=$(_find -type f "$file")
+        echo -n "There isn't a file called \`$file\` in your current directory."
+        if [[ ! -z "$dir" ]]; then
+            echo " Did you mean to run \`cd $dir\` first?"
+        else
+            echo
+        fi
+        exit
+    fi
+fi
diff --git a/opt/cs50/lib/help50/python b/opt/cs50/lib/help50/python
new file mode 100755
index 0000000..1d8b3fd
--- /dev/null
+++ b/opt/cs50/lib/help50/python
@@ -0,0 +1,64 @@
+#!/bin/bash
+
+. /opt/cs50/lib/cli
+
+output=$(cat)
+
+# touch cs50.py && python -c "import cs50; cs50.get_int" && python -c "from cs50 import get_int"
+regex="AttributeError: module 'cs50' has no attribute '.*'|ImportError: cannot import name '.*' from 'cs50'"
+if [[ "$output" =~ $regex ]]; then
+    if [[ -f cs50.py ]]; then
+        echo "You have a file called \`cs50.py\` that is \"shadowing\" CS50's own. Best to rename that file with \`mv\`."
+        exit
+    fi
+fi
+
+# touch re.py && python -c "import re; re.search" && python -c "from re import search"
+regex="AttributeError: module 're' has no attribute '.*'|ImportError: cannot import name '.*' from 're'"
+if [[ "$output" =~ $regex ]]; then
+    if [[ -f re.py ]]; then
+        echo "You have a file called \`re.py\` that is \"shadowing\" Python's own. Best to rename that file with \`mv\`."
+        exit
+    fi
+fi
+
+# touch re.py && python -c "import string; string.digits" && python -c "from string import digits"
+regex="AttributeError: module 'string' has no attribute '.*'|ImportError: cannot import name '.*' from 'string'"
+if [[ "$output" =~ $regex ]]; then
+    if [[ -f string.py ]]; then
+        echo "You have a file called \`string.py\` that is \"shadowing\" Python's own. Best to rename that file with \`mv\`."
+        exit
+    fi
+fi
+
+# mkdir -p foo/bar && touch foo/bar/baz.py && python baz.py
+regex="python: can't open file '(.*\.py)': \[Errno 2\] No such file or directory"
+if [[ "$output" =~ $regex ]]; then
+
+    # Relative path from $PWD
+    path=$(realpath --relative-to=. "${BASH_REMATCH[1]}")
+
+    # If command was `python baz.py` (i.e., without a dirname)
+    if [[ -n "$path" && "$path" == $(basename "$path") ]]; then
+        dir=$(_find -type f "$path")
+        echo -n "There isn't a file called \`$path\` in your current directory."
+        if [[ ! -z "$dir" ]]; then
+            echo " Did you mean to \`cd $dir\` first?"
+        else
+            echo
+        fi
+        exit
+    fi
+
+    # If command was `python bar/baz.py` (i.e., with a dirname)
+    if [[ -n "$path" && "$path" == $(basename "$path") ]]; then
+        dir=$(_find -type f "$path")
+        echo -n "There isn't a file called \`$path\` in your current directory."
+        if [[ ! -z "$dir" ]]; then
+            echo " Did you mean to \`cd $dir\` first?"
+        else
+            echo
+        fi
+        exit
+    fi
+fi