exec: 'command': executable file not found in $PATH

The error “exec: ‘command’: executable file not found in $PATH” occurs during a RUN instruction in a Dockerfile when the specified command is not available inside the container image.

What It Means

Docker builds each layer by running a command in a temporary container based on the previous layer. When a RUN instruction references a command that is not installed in the container, the shell or exec form returns this error and the build fails immediately.

Why It Happens

• The base image is minimal (e.g., alpine, scratch, distroless) and does not include common tools.
• The command name is misspelled or the wrong package provides it.
• The RUN instruction appears before the package install command.
• The command was installed in a previous RUN but the image was cached and the cache was invalidated.
• The exec form (RUN ["command", "arg"]) is used but the command is not in PATH.

How to Fix It

1. Use the exec form with the full path

RUN ["/usr/bin/curl", "-sL", "https://example.com"]

2. Install the missing package

RUN apt-get update && apt-get install -y curl

3. For Alpine, use apk

RUN apk add --no-cache curl

4. Check what is in the base image

RUN which command_name  # debug: see if it exists

5. Combine RUN instructions to avoid ordering issues

RUN apt-get update && apt-get install -y \
    curl \
    git \
    && rm -rf /var/lib/apt/lists/*

FAQ