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chore(kb/make): check variables are set

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This commit is contained in:
Michele Cereda
2024-04-01 19:03:49 +02:00
parent 30e8401b2c
commit 1efa43de66
1 changed files with 13 additions and 7 deletions
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20
knowledge base/gnu userland/make.md
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@@ -8,8 +8,8 @@
## TL;DR
```makefile
# assign default values, but allow override
# usage: make override_me=new_value target
# Assign default values, but allow override.
# Usage: `make override_me=new_value target`.
override override_me ?= default_value
@@ -19,18 +19,21 @@ include .env
-include .env.local .env.extra
# export variables for all programs to see
# only exported in the commands' sub-shells
# Export variables for all programs to see.
# Only exported in the commands' sub-shells.
export
# export specific variables only
# Export specific variables only.
export override_me
# assign shell command output as values
# Assign shell command outputs as values.
command_output = ${shell command with args}
# Target-specific variables.
# Call targets from targets.
# Check variables are set.
target_name: target_specific_variable = value
target_name: dash_instead_of_underscore = ${subst _,-,${override_me}}
target_name: previous_target required_file.ext
@@ -43,9 +46,10 @@ previous_target:
@quiet_command
next_target:
@[ "${var}" ] && echo "all good" || ( echo "var is not set"; exit 1 )
# conditionals
# Conditionals.
ifeq "${shell uname}" "Darwin"
expiration_date = ${shell date -v "+365d" "+%FT%TZ"}
else ifeq "${shell uname}" "Linux"
@@ -113,6 +117,7 @@ If prefixed with '-' (`-include`), it does not error nor warning should any of t
- [Makefile variable initialization and export]
- [How to load and export variables from an .env file in Makefile?]
- [Check a variable is set and fail otherwise]
<!--
References
@@ -123,5 +128,6 @@ If prefixed with '-' (`-include`), it does not error nor warning should any of t
[include]: https://www.gnu.org/software/make/manual/html_node/Include.html
<!-- Others -->
[Check a variable is set and fail otherwise]: https://stackoverflow.com/questions/38801796/how-to-conditionally-set-makefile-variable-to-something-if-it-is-empty#56193440
[how to load and export variables from an .env file in makefile?]: https://stackoverflow.com/questions/44628206/how-to-load-and-export-variables-from-an-env-file-in-makefile#70663753
[makefile variable initialization and export]: https://stackoverflow.com/questions/2838715/makefile-variable-initialization-and-export