Wrong ANSI font representation

[literally-user]

Description

When running make outside the container, the following warning is displayrd:
\033[1mWARNING\033[0m: you are not in a container.

Reproduce

1. make binary

Expected behavior

The warning text should be displayed in bold correctly in all POSIX-compliant shells

docker version

Client:
 Version:           29.2.1
 API version:       1.53
 Go version:        go1.25.6 X:nodwarf5
 Git commit:        a5c7197d72
 Built:             Thu Feb  5 10:59:55 2026
 OS/Arch:           linux/amd64
 Context:           default

Server:
 Engine:
  Version:          29.2.1
  API version:      1.53 (minimum version 1.44)
  Go version:       go1.25.6 X:nodwarf5
  Git commit:       6bc6209b88
  Built:            Thu Feb  5 10:59:55 2026
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v2.2.1
  GitCommit:        dea7da592f5d1d2b7755e3a161be07f43fad8f75.m
 runc:
  Version:          1.4.0
  GitCommit:        
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client:
 Version:    29.2.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  0.31.1
    Path:     /usr/lib/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  5.1.0
    Path:     /usr/lib/docker/cli-plugins/docker-compose

Server:
 Containers: 5
  Running: 0
  Paused: 0
  Stopped: 5
 Images: 41
 Server Version: 29.2.1
 Storage Driver: overlayfs
  driver-type: io.containerd.snapshotter.v1
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: dea7da592f5d1d2b7755e3a161be07f43fad8f75.m
 runc version: 
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.18.8-arch2-1-surface
 Operating System: Arch Linux
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 15.54GiB
 Name: literally
 ID: 4e2fe906-d9d1-4e04-9512-ba13d86dce56
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false
 Firewall Backend: iptables

Additional Info

in POSIX sh (and also on some systems, including macos and bsd) echo does not interpret escape sequences by default, and the -e flag is not standardized behavior. And because of this outputting colors via echo does not work on all systems

I propose replacing the use of echo for ANSI colors with printf, which is guaranteed to interpret correctly on all POSIX-compliant systems.

like this:

				(
						printf "\n"
						printf "\033[1mWARNING\033[0m: you are not in a container."
						printf
						printf 'Use "\033[1mmake dev\033[0m" to start an interactive development container,'
						printf "use \"\033[1mmake -f docker.Makefile $target\033[0m\" to execute this target"
						printf "in a container, or set \033[1mDISABLE_WARN_OUTSIDE_CONTAINER=1\033[0m to"
						printf "disable this warning."
						printf
						printf "Press \033[1mCtrl+C\033[0m now to abort, or wait for the script to continue.."
						printf "\n"
				) >&2