Alpine: Executables

Various helper executables for providing standard output and simplifying common tasks.

Output

bf-debug

Echoes "$1: $2" to stdout in grey with prefix (see bf-e) - but only if environment variable BF_DEBUG is set to "1".

Arguments

1. Text to output

2. [Optional] Script / executable name

Usage

$ bf-debug "Hi"
[bf] 2021-09-19 18:00:00 | Hi # (in grey)

$ bf-debug "Hi" "alpine-s6/docs"
[bf] 2021-09-19 18:00:00 | alpine-s6/docs: Hi # (in grey)

bf-done

Echoes 'done.' to stdout in green with prefix (see bf-ok).

Arguments

1. [Optional] Script / executable name

Usage

$ bf-done
[bf] 2021-09-19 18:00:00 | done. # (in green)

$ bf-done "alpine-s6/docs"
[bf] 2021-09-19 18:00:00 | alpine-s6/docs: done. # (in green)

bf-e

Echoes $3 to stdout in colour $2 with prefix: "[$1] %Y-%m-%d %H:%M:%S".

Arguments

1. Namespace (default value for other output helper executables is 'bf')

2. ANSI colour code (see e.g. here)
3. Text to output

4. [Optional] Script / executable name

Usage

$ bf-e "docs" "\e[91m" "Hi"
[docs] 2021-09-19 18:00:00 | Hi # (in red)

$ bf-e "docs" "\e[92m" "Hi" "alpine-s6"
[docs] 2021-09-19 18:00:00 | alpine-s6: Hi # (in green)

bf-echo

Echoes "$1: $2" to stdout in default colour with prefix (see bf-e).

Arguments

1. Text to output

2. [Optional] Script / executable name

Usage

$ bf-echo "Hi"
[bf] 2021-09-19 18:00:00 | Hi # (in black / white)

$ bf-echo "Hi" "docs"
[bf] 2021-09-19 18:00:00 | docs: Hi # (in black / white)

bf-error

Echoes "$1: $2" to stdout in red with prefix (see bf-e), and returns 1. This will end execution of the calling script if you use, e.g. set -euo pipefail at the top of your scripts (recommended).

Arguments

1. Text to output

2. [Optional] Script / executable name

Usage

$ bf-error "Die"
[bf] 2021-09-19 18:00:00 | Die # (in red)

$ bf-error "Die" "docs"
[bf] 2021-09-19 18:00:00 | docs: Die # (in red)

bf-notok

Like bf-error echoes "$1: $2" to stdout in red with prefix, but doesn't end execution of calling script.

Arguments

1. Text to output

2. [Optional] Script / executable name

Usage

$ bf-notok "Error"
[bf] 2021-09-19 18:00:00 | Error # (in red)

$ bf-notok  "Error" "docs"
[bf] 2021-09-19 18:00:00 | docs: Error # (in red)

bf-ok

Echoes "$1: $2" to stdout in green with prefix.

Arguments

1. Text to output

2. [Optional] Script / executable name

Usage

$ bf-ok "Hi"
[bf] 2021-09-19 18:00:00 | Hi # (in green)

$ bf-ok  "Hi" "docs"
[bf] 2021-09-19 18:00:00 | docs: Hi # (in green)

Helpers

bf-adduser

Create user with id $2, group with id $3, both with name $1, and no password.

Arguments

1. User and group name

2. [Optional] User ID (default: 1000)

3. [Optional] Group ID (default: UID)

Usage

$ bf-adduser "fred"
[bf] 2021-09-19 18:00:00 | bf-adduser: Adding user and group 'fred'...
[bf] 2021-09-19 18:00:00 | bf-adduser: done. 'fred'... # (in green)
$ cat /etc/passwd
...
fred:x:1000:1000:Linux User,,,:/home/fred:/bin/ash

$ bf-adduser "fred" 1001
[bf] 2021-09-19 18:00:00 | bf-adduser: Adding user and group 'fred'...
[bf] 2021-09-19 18:00:00 | bf-adduser: done. 'fred'... # (in green)
$ cat /etc/passwd
...
fred:x:1001:1001:Linux User,,,:/home/fred:/bin/ash

$ bf-adduser "fred" 1002 1003
[bf] 2021-09-19 18:00:00 | bf-adduser: Adding user and group 'fred'...
[bf] 2021-09-19 18:00:00 | bf-adduser: done. 'fred'... # (in green)
$ cat /etc/passwd
...
fred:x:1002:1003:Linux User,,,:/home/fred:/bin/ash

bf-ch

Changes ownership and/or permissions of file / directory glob.

Arguments

Required (one or both):

• -o X use chown to set ownership to "X"

• -m Y use chmod to set permissions to "Y"

Optional:

• -t f|d apply only to files ("f") or directories ("d")

• -rif -t is not specified, applies action recursively to all files and directories

Usage

$ bf-ch -o "fred" -m 777 -t f /tmp
[bf] 2021-09-19 18:00:00 | bf-ch: Applying chown fred to /tmp.
[bf] 2021-09-19 18:00:00 | bf-ch:  .. type f.
[bf] 2021-09-19 18:00:00 | bf-ch: Applying chmod 777 to /tmp.
[bf] 2021-09-19 18:00:00 | bf-ch:  .. type f.

$ bf-ch -o "fred" -m 777 -r /tmp
[bf] 2021-09-19 18:00:00 | bf-ch: Applying chown fred to /tmp.
[bf] 2021-09-19 18:00:00 | bf-ch:  .. recursively.
[bf] 2021-09-19 18:00:00 | bf-ch: Applying chmod 777 to /tmp.
[bf] 2021-09-19 18:00:00 | bf-ch:  .. recursively.

bf-clear

Clears contents of /tmp and apk cache.

Usage

$ bf-clear
[bf] 2021-09-19 18:00:00 | bf-clear: Clearing /tmp...
[bf] 2021-09-19 18:00:00 | bf-clear: done.
[bf] 2021-09-19 18:00:00 | bf-clear: Clearing caches...
[bf] 2021-09-19 18:00:00 | bf-clear: done.

bf-esh

Calls esh in a consistent manner.

Arguments

1. Path to input (template) file

2. Path to output (generated) file

Usage

$ bf-esh /path/to/template /path/to/output
[bf] 2021-09-19 18:00:00 | bf-esh: /path/to/output created.

bf-image

Display name and version of the current image, and a link to the GitHub repository.

Usage

$ bf-image
[bf] 2021-09-19 18:00:00 | bf-image: bfren alpine 1.2.0.
[bf] 2021-09-19 18:00:00 | bf-image: https://github.com/bfren/docker-alpine.

bf-install

Run install /tmp/install and then perform cleanup (see bf-clear). Within the ecosystem this would normally be used in a Dockerfile

Usage

This is the basic structure of Dockerfiles based on the Alpine S6 image, copying overlay and then running the standard installation.

FROM bfren/alpine-s6:alpine3.14

COPY ./overlay /

RUN bf-install

bf-rmrf

Runs rm -rf $1 safely: doing nothing if $1 is empty. This is handy if the path you are deleting is contained in a variable (it effectively stops rm -rf /!).

Arguments

1. Folder path / file glob to delete.

Usage

$ bf-rmrf ""
[bf] 2021-09-19 18:00:00 | bf-rmrf: Cannot remove ''.

bf-rmrf /tmp/*
[bf] 2021-09-19 18:00:00 | bf-rmrf: Removing /tmp/*.

bf-rnd

Generates a string of random letters and numbers of length $1.

Arguments

1. [Optional] Number of characters to return

Usage

$ bf-rnd
7ceeezFaFzbuaHujA2ST2s3ACPAnAEoUqqVXBcdk

$ bf-rnd 10
D8ORzTX56m

$ RND=$(bf-rnd)
$ echo ${RND}
cm1HuNlkQwbqd5TeApoHsxfYE6X1MWxKnuiBbjFr

bf-test-url

Uses wget to test URL $1.

Arguments

1. URL to test

Usage

$ bf-test-url https://fake.url
[bf] 2021-09-19 18:00:00 | bf-test-url: Loading https://fake.url.
wget: bad address 'fake.url'

$ bf-test-url https://bbc.co.uk
[bf] 2021-09-19 18:00:00 | bf-test-url: Loading https://bbc.co.uk.
Connecting to bbc.co.uk (151.101.0.81:443)
Connecting to www.bbc.co.uk (212.58.237.254:443)
remote file exists

bf-tz

Sets the container's timezone to $1. (Installs tzdata package, changes timezone and then removes tzdata).

Arguments

1. Valid timezone (e.g. Europe/London)

Usage

Note the change in time on line 12.

$ bf-tz UTC
[bf] 2021-09-19 18:00:00 | bf-tz: Installing tzdata packages.
fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz
(1/2) Installing tzdata (2021a-r0)
(2/2) Installing .tz (20210923.092854)
Executing busybox-1.33.1-r3.trigger
OK: 9 MiB in 17 packages
[bf] 2021-09-19 18:00:00 | bf-tz: Setting timezone to UTC...
[bf] 2021-09-19 17:00:00 | bf-tz: Removing tzdata packages.
(1/2) Purging .tz (20210923.092854)
(2/2) Purging tzdata (2021a-r0)
Executing busybox-1.33.1-r3.trigger
OK: 6 MiB in 15 packages
[bf] 2021-09-19 17:00:00 | bf-tz: done.

$ cat /etc/localtime
TZif2
UTCTZif2
UTC
UTC0