N.B. If you're interested in building Midipix using this script, please join the project's IRC channel #midipix on Libera and ask for the address of the internal repositories required in order to build Midipix.

N.B. Due to the present state of the (largely) automated package upstream updates integration script and, despite frequent contributions, lack of human resources, it bears mentioning that the 3rd party packages built and distributed by this script are often not up to date with their resp. upstream and may hence be insecure. It is advised that this be taken into account when deploying and using Midipix distributions.

Table of Contents

1. What is Midipix, and how is it different?
2. Building and deployment
   2.1. Building, installing, and using a Midipix distribution
   2.1.1. Build-time dependencies
   2.1.1.1. Alpine-specific notate bene
   2.2. Deployment
   2.3. System requirements
   2.4. Troubleshooting
3. Common concepts and tasks / FAQ
   3.1. Common tasks
   3.2. Adding a package
   3.3. Addressing build failure
   3.4. Package archive files and Git repositories
   3.5. Patches and vars files
4. Reference
   4.1. Build steps
   4.2. Build variables
   4.3. File installation DSL
   4.4. Package variables
   4.4.1. Package variable types
   4.4.2. Package variables
   4.5. Fault-tolerant & highly optimised 3D laser show-equipped usage screen
   4.6. pkgtool.sh
   4.7. Bourne shell coding rules
5. References

1. What is Midipix, and how is it different?

midipix is a development environment that lets you create programs for Windows using the standard C and POSIX APIs. No compromises made, no shortcuts taken.

If you are interested in cross-platform programming that reclaims the notion of write once, compile everywhere; if you believe that the 'standard' in the C Standard Library should not be a null signifier; and if you like cooking your code without #ifdef hell and low-level minutiae, then this page is for you.

midipix makes cross-platform programming better, simpler and faster, specifically by bringing a modern, conforming C Runtime Library to the Windows platform. While the idea itself is not new, the approach taken in midipix to code portability is radically different from that found in other projects.

(reproduced from [2])

Back to top

2. Building and deployment

2.1. Building, installing and using a Midipix distribution

A Midipix distribution consists of the following:

• the native Midipix toolchain, consisting of perk, gcc, its dependencies, and binutils,
• musl, a lightweight, fast, simple, and free libc[1] used by Midipix,
• the Midipix runtime components that bridge the gap between the libc and the executive subsystems of all Windows NT-derived Windows OS starting with and including Windows XP, and
• a steadily increasing number of 3rd party open source packages, as expected in any modern POSIX-compliant *nix environment, including GNU coreutils, shells, libraries such as ncurses, libressl, as well as Perl and Python.

Install the build-time dependencies listed in section 2.1.1, clone this repository (e.g. git clone https://dev.midipix.org/build/midipix_build) and run the following command line:

./build.sh -a nt64 -b release -D zipdist -P -v

By default, the build will take place within ${HOME}/midipix/nt64/release and package archive files and/or Git repositores will be downloaded into ${HOME}/midipix/dlcache. Consult sections 4.2 and 4.4 for the list of available build/package variables and how to override them.
Parallelisation is enabled by the above command line for both packages that can be built independently of each other and make(1) via -j, limited to the amount of logical processors on the build host divided by two (2).

Back to top

2.1.1. Build-time dependencies

• Alpine Linux: binutils bison bzip2 cmake coreutils curl findutils g++ gawk gcc git grep gzip libc-dev linux-headers lzip m4 make musl-dev net-tools patch perl perl-xml-parser procps sed tar util-linux util-linux-dev wget xz zip
• Arch Linux: binutils bison bzip2 cmake coreutils curl findutils gawk gcc git grep gzip lzip m4 make net-tools patch perl perl-xml-parser procps-ng sed tar util-linux util-linux-libs wget xz zip
• Debian/-derived Linux: binutils bison bzip2 cmake coreutils curl findutils g++ gawk gcc git grep gzip hostname libc6-dev libxml-parser-perl lzip m4 make patch perl procps sed tar util-linux uuid-dev wget xz-utils zip
• Gentoo Linux: binutils bison bzip2 cmake coreutils curl findutils gawk =gcc-7.5.0-r1 dev-vcs/git grep gzip lzip m4 make patch perl dev-perl/XML-Parser procps sed tar util-linux libuuid wget xz-utils zip
• OpenSUSE Linux: binutils bison bzip2 cmake coreutils curl findutils gawk gcc gcc-c++ git grep gzip hostname linux-glibc-devel lzip m4 make patch perl perl-XML-Parser procps sed tar util-linux libuuid1 wget xz zip

The distro matrix:

Alpine Linux:	Arch Linux:	Debian/-derived Linux:	Gentoo Linux:	OpenSUSE Linux:
binutils	binutils	binutils	binutils	binutils
bison	bison	bison	bison	bison
bzip2	bzip2	bzip2	bzip2	bzip2
cmake	cmake	cmake	cmake	cmake
coreutils	coreutils	coreutils	coreutils	coreutils
curl	curl	curl	curl	curl
findutils	findutils	findutils	findutils	findutils
g++	-	g++	-	gcc-c++
gawk	gawk	gawk	gawk	gawk
gcc	gcc	gcc	=gcc-7.5.0-r1	gcc
git	git	git	dev-vcs/git	git
grep	grep	grep	grep	grep
gzip	gzip	gzip	gzip	gzip
-	-	hostname	-	hostname
libc-dev	-	libc6-dev	-	linux-glibc-devel
linux-headers	-	-	-	-
lzip	lzip	lzip	lzip	lzip
m4	m4	m4	m4	m4
make	make	make	make	make
musl-dev	-	-	-	-
net-tools	net-tools	-	-	-
patch	patch	patch	patch	patch
perl	perl	perl	perl	perl
perl-xml-parser	perl-xml-parser	libxml-parser-perl	dev-perl/XML-Parser	perl-XML-Parser
procps	procps-ng	procps	procps	procps
sed	sed	sed	sed	sed
tar	tar	tar	tar	tar
util-linux	util-linux	util-linux	util-linux	util-linux
util-linux-dev	util-linux-libs	uuid-dev	libuuid	libuuid1
-	vi	-	-	-
wget	wget	wget	wget	wget
xz	xz	xz-utils	xz-utils	xz
zip	zip	zip	zip	zip

N.B. Busybox is not supported. Awk implementations other than GNU Awk are not supported.

N.B. clang is not supported.

Back to top

2.1.1.1. Alpine-specific notate bene

Some packages (coreutils, grep, and tar, among others) override Alpine's BusyBox utilities of the same name, as the latter are either non-conformant or defective.

Back to top

2.2. Deployment

On successful completion of the build, a ZIP archive containing the Midipix distribution will be created inside ${PREFIX} (see section 4.2.) Create a directory on the target machine and extract the contents of the distribution ZIP archive into it, run bash.bat, and then /install.sh inside the resulting self-contained Midipix installation shell window.

Make sure to consult the notate bene below:

N.B. The pathname of the target directory containing bash.bat and all other distribution files must not contain whitespaces.

N.B. The Midipix installer defaults to /dev/fs/c/midipix (C:\midipix). If left unchanged, the distribution ZIP archive must not be extracted into a directory of the same pathname.

N.B. The user installing and using Midipix must have been delegated the SeCreateSymbolicLinkPrivilege ("Create symbolic links") privilege[3] and additionally be a non-administrator account owing to the UAC-related filtering policy of tokens introduced by Windows Vista[4].

N.B. On Windows 10 and 11, Windows Defender as well as SmartScreen must be disabled.

Back to top

2.3. System requirements

The following build-time system requirements are assessed on build hosts equipped with the following hardware at minimum:

• Intel(R) Xeon(R) CPU W3520 @ 2.67GHz (8 cores)
• 7200 RPM SATA 3.1 HDD
• 6 GB RAM

Target architecture	Build kind	Distribution kinds selected	Average build time	Disk space required	Peak RAM usage
nt64	debug	(none)	2 hours	57.62 GB	3.55 GB
nt64	release	(none)	1 hours 45 minutes	36.51 GB	3.21 GB

Package archive files and/or Git repositories additionally consume at least 1.82 GB.

(last update: Thu, 05 Mar 2020 09:25:41 +0000)

These are the Midipix distribution disk space system requirements:

Target architecture	Build kind	Distribution	Installation directory	Archive file
nt64	debug	7.3 GB	2.3 GB	2.1 GB
nt64	release	3.2 GB	913 MB	830 MB

The installation directory and archive file may be safely deleted post-installation.

(last update: Thu, 07 Jan 2021 18:20:06 +0000)

Back to top

2.4. Troubleshooting

Midipix presently provides, inter alia, strace-like functionality via ntctty's logging capabilities. This is available both through the regular strace(1) command as distributed, which however must be provided with an absolute pathname without consideration for ${PATH}, as well as directly via ntctty.exe for a session by running ntctty.exe with the --log-level 7 option, e.g.:

$ #strace ls -la /        # (incorrect, relative pathname)
$ strace /bin/ls -la /    # (correct, absolute pathname)
$ ntctty.exe --log-level 7 -e /bin/ls -la /
$ ntctty.exe --log-level=7 -e /bin/ls -la /
$ ntctty.exe --log-level 7 -e /bin/sh -c "ls -la /"
$ ntctty.exe --log-level=7 -e /bin/sh -c "ls -la /"

By default, ntctty.exe log files are written into the /var/log/ntctty directory; this may be adjusted with the --log-dir and/or --log-file options. strace(1) logs to stderr by default.

Back to top

3. Common concepts and tasks

3.1. Common tasks

Rebuild set of packages in isolation:

./build.sh [ ... ] -r mc,zsh

Restart the @install (shorthand alias) step, with implicit finish, of the mc and zsh packages.

./build.sh [ ... ] -r mc,zsh:@install

Rebuild set of packages along w/ their dependencies, if any, as needed, or forcibly, respectively:

./build.sh [ ... ] -r \*mc,zsh
./build.sh [ ... ] -r \*\*mc,zsh

Forcibly rebuild all reverse dependencies of a set of packages:

./build.sh [ ... ] -r \*\*\*glib,libflac

Restart the @configure, @build, and @install (shorthand alias) steps of the coreutils package:

./build.sh -r coreutils:@configure,@build,@install

Rebuild entire build groups including or excluding group dependencies, respectively:

./build.sh [ ... ] -r ALL native_runtime
./build.sh [ ... ] -r ALL =native_runtime

Forcibly (re)download all archive files and/or Git repositories associated with all packages:

./build.sh [ ... ] -r ALL:@fetch,finish

N.B. the "finish" (pseudo-)build step must be included here and in similar use cases so that all affected packages are marked as having finished building in order to correctly satisfy package-package dependencies.

Back to top

3.2. Adding a package

Packages are grouped into build groups according to sets of common package variable defaults, such as ${PKG_CFLAGS_CONFIGURE}, ${PKG_LDFLAGS_CONFIGURE} and ${PKG_CONFIGURE_ARGS}, and semantic interrelatedness, such as the native_runtime build group comprising the Midipix runtime components. Packages may belong to more than one build group such as when subsumed by a shorthand build group e.g. the dev_packages build group, as long as the default set of build groups or as overriden on the command line does not entail group membership conflicts.

Build groups files beneath groups.d/ named [0-9][0-9][0-9].<group name>.group contain package variable defaults, optionally the alphabetically sorted list of contained packages, if any, in <upper case group name>_PACKAGES, and their package variables sorted alphabetically with the exception of ${PKG_DEPENDS} (if present,) ${PKG_SHA256SUM}, ${PKG_URL}, and ${PKG_VERSION}, and/or ${PKG_URLS_GIT}, which are specified in this order. Build group files require the following epilogue, the parameters enclosed in square brackets being optional:

ex_pkg_register_group "<group name>" "${RTL_FILEOP_SOURCE_FNAME}" [["owner|copy"] ["auto|noauto"]];

# vim:filetype=sh textwidth=0

If copy is specified, the build group will copy all of its packages from their respective build groups without taking ownership thereof, if owner is specified, the default, the build group owns all of its packages. If noauto is specified, the build group will not be added to the list of build groups to build by default, if auto is specified, the build group will be added to the list of build groups to build by default.

If a build group that specifies copy should copy all of its build group variables from another build group, use the following code:

ex_pkg_copy_group_vars "<source group name>" "<destination group name>";

Additionally, single package files may be added beneath groups.d/[0-9][0-9][0-9].<group name>.d/, named <package name>.package containing the package's variables, with the following epilogue, the parameters enclosed in square brackets being optional:

ex_pkg_register "<package_name>" "${RTL_FILEOP_SOURCE_FNAME}" ["<group name>"];

# vim:filetype=sh textwidth=0

1. Pick a build group according to the criteria mentioned and specifiy the set of package variables required (see above and section 4.4) in either the corresponding group file or a single package file; in the former case, do also add the package to the build group's list of contained packages.

2. Consult section 3.5 if the package to be added requires patches or additional code amending or replacing package build steps or the entire package build. Consult section 4.1 for a list of package build steps and how they are overriden.

Back to top

3.3. Addressing build failure

During package build, standard error and output are redirected into a log file beneath ${BUILD_WORKDIR} named ${PKG_NAME}_stderrout.log, following a package variable dump. If -V build was specified, package logs will additionally be printed to standard output. If -V xtrace was specified, xtrace will be set during package builds for rudimentary debugging purposes. Additionally, packages using GNU autotools will, if package configuration failed or appears relevant, log the configuration process in detail in, most usually, ${PKG_BUILD_DIR}/config.log.

Back to top

3.4. Package archive files and Git repositories

Packages may have either or both of a SHA-256 message digest checked and to be extracted tarball (set in ${PKG_URL}, ${PKG_FNAME}, and ${PKG_SHA256SUM}) and/or Git repository or set thereof (set in ${PKG_URLS_GIT}.) Complementing these, an implicitly inferred or, in the presence of both, explicit primary source directory is specified for each package in ${PKG_SUBDIR}. Furthermore, these may be subject to download caching and/or setting up as well as maintaining mirrors, including automatic cleanup as well as deduplication in both cases.

A list of pertinent package variables and their formats follows:

Name	Format
PKG_FNAME	<single file name>
PKG_SHA256SUM	<SHA-256 message digest>
PKG_SUBDIR	<relative or single directory name>
PKG_URL	scheme:[//authority]path[?query][#fragment]
PKG_URLS_GIT	[subdir=]URL[@branch]

Back to top

3.5. Patches and vars files

Package patches are applied prior and/or subsequent to (GNU autotools or similar) package configuration during the configure_patch_pre and/or configure_patch build steps, respectively (see section 4.1.) Patch files are searched for beneath patches/ with the following globs and in-order:

• ${PKG_NAME}-${PKG_VERSION}_pre.local.patch or ${PKG_NAME}_pre.local.patch (for packages lacking ${PKG_VERSION})
• ${PKG_NAME}-${PKG_VERSION}_pre.local@${BUILD_HNAME}.patch or ${PKG_NAME}_pre.local@${BUILD_HNAME}.patch (for packages lacking ${PKG_VERSION})
• ${PKG_NAME}/*.patch
• ${PKG_NAME}-${PKG_VERSION}.local.patch or ${PKG_NAME}.local.patch (for packages lacking ${PKG_VERSION})
• ${PKG_NAME}-${PKG_VERSION}.local@${BUILD_HNAME}.patch or ${PKG_NAME}.local@${BUILD_HNAME}.patch (for packages lacking ${PKG_VERSION})
• ${PKG_PATCHES_EXTRA} (if set)

If the default set of package build steps does not suffice, such as if additional commands must be executed after package configuration or prior to building, or if an entire or all build step must be replaced, overrides may be specified in the form of functions in the package's vars/${PKG_NAME}.vars as well as vars.<group name>/${PKG_NAME}.vars vars file(s). Consult section 4.1 for a list of package build steps and how they are overriden.

Back to top

4. Reference

4.1. Build steps

Package builds are divided up into consecutively executed build steps until completion or aborted on failure unless relaxed mode is enabled by passing -R.

Each build step corresponds to a function in the corresponding subr/pkg_*.subr script and may be overriden entirely by a function named pkg_<package name>_<build step>() or composed in terms of prior and/or subsequent execution by a function named pkg_<package name>_<build step>_pre() and/or pkg_<package name>_<build step>_post(), respectively, in the package's vars file. If a function named pkg_<package name>_all() exists, it will override all build steps.

Build step functions receive the following arguments in the order specified:

Name	Description
_group_name	Package name
_pkg_name	Group name
_restart_at	Optional list of build steps to restart package build at

Build step status is tracked on a per-package basis by state files beneath ${BUILD_WORKDIR} following the format .<package name>.<build step>; package build completion corresponds to the pseudo-build step finish.

Name	Description
fetch_clean	Delete and create ${PKG_SUBDIR}
fetch_download	Download package archive & verify w/ SHA-256 message digest and/or clone Git repository/ies
fetch_extract	Extract package archive, if any
configure_clean	Delete and create ${PKG_BUILD_DIR}
configure_patch_pre	Apply chainport patches and/or patches beneath patches/ prior to (GNU autotools or similar) configuration
configure_autotools	Bootstrap (GNU autools or similar) environment, and install config.sub and config.cache
configure_patch	Apply patches beneath patches/ and/or set in ${PKG_PATCHES_EXTRA} after (GNU autotools or similar) configuration
configure	Perform package (GNU autools or similar or CMake) configuration w/ configuration-time set of environment variables
build_clean	Clean ${PKG_BUILD_DIR} w/ make clean invocation
build	Call make(1) w/ build-time set of make variables
install_clean	Delete and create ${PKG_DESTDIR}
install_subdirs	Create default directory hierarchy in ${PKG_DESTDIR}, optionally amended w/ ${PKG_INSTALL_FILES_DESTDIR_EXTRA}
install_make	Call make(1) w/ ${PKG_INSTALL_TARGET} (defaults to install) and installation-time set of make variables
install_files	Install ${PKG_INSTALL_FILES} and/or ${PKG_INSTALL_FILES_V2}, fix directory and file mode bits within ${PKG_DESTDIR} and optionally ${PKG_DESTDIR_HOST}, pkgconf(1) package files, and/or stripped binaries within ${PKG_DESTDIR}
	Purge libtool .la files and install shared objects within ${PKG_DESTDIR} w/ perk and corresponding symbolic links
install	Install into ${PKG_PREFIX}, and optionally ${PKG_DESTDIR_HOST} into ${PREFIX}, under mutex, and add package to ${PREFIX}/pkglist.${PKG_BUILD_TYPE} (unless inhibited)
install_rpm	Build package RPM w/ auto-generated specifiation file based on etc/package.spec beneath ${PREFIX_RPM}
clean	Clean ${PKG_BUILD_DIR} and/or ${PKG_DESTDIR} and/or ${PKG_DESTDIR_HOST} and/or ${PKG_BASE_DIR}/${PKG_SUBDIR} as per -C build,dest,src, resp., if any

Back to top

4.2. Build variables

The following variables are primarily defined in vars.env.d/*.env and may be overriden on a per-build basis on the command-line, the environment, and/or ${HOME}/midipix_build.vars, ${HOME}/.midipix_build.vars, and/or ../midipix_build.vars, e.g.:

./build.sh -a nt64 -b release -D minipix,zipdist -P -v PREFIX_ROOT="${HOME}/midipix_tmp"
env ARCH=nt64 BUILD_KIND=release PREFIX_ROOT="${HOME}/midipix_tmp" ./build.sh -D minipix,zipdist -P -v

Variable name	Default value	Description
ARCH	nt64	Target 32-bit (nt32) or 64-bit (nt64) architecture
BUILD_DLCACHEDIR	${PREFIX_ROOT}/dlcache	Absolute pathname to package downloads cache root directory
BUILD_HNAME	$(hostname)	Build system hostname
BUILD_KIND	debug	Build w/ debugging (debug) or release compiler flags
PREFIX_LOCAL	${PREFIX}/localcross	Absolute pathname to local cross-toolchain root directory
BUILD_WORKDIR	${PREFIX}/tmp	Absolute pathname to temporary package build root directory
PREFIX	${PREFIX_ROOT}/${ARCH}/${BUILD_KIND}	Absolute pathname to architecture- & build type-specific build root directory
PREFIX_CROSS	${PREFIX}/${DEFAULT_TARGET}	Absolute pathname to toolchain root directory
PREFIX_MINGW32	${PREFIX}/x86_64-w64-mingw32	Absolute pathname to MinGW toolchain root directory
PREFIX_MINIPIX	${PREFIX}/minipix	Absolute pathname to minipix distribution root directory
PREFIX_NATIVE	${PREFIX}/native	Absolute pathname to cross-compiled packages root directory
PREFIX_ROOT	${HOME}/midipix	Absolute pathname to top-level directory
PREFIX_RPM	${PREFIX}/rpm	Absolute pathname to package RPM archive root directory

Back to top

4.3. File installation DSL

File and directory installation, comprising e.g. copying, moving, creating symbolic links, setting owner and/or permission metadata, are expressed in a descriptive domain-specific language and integrated with package building via the package variable ${PKG_INSTALL_FILES_V2}, applying during install_files after the install_make build step, and ${PKG_INSTALL_FILES_DESTDIR} and ${PKG_INSTALL_FILES_DESTDIR_EXTRA} during install_subdirs. The ${PKG_INSTALL_FILES_V2} must adhere to the following syntax specified in EBNF:

(*
SH_GLOB_PATTERN      = any valid portable shell pattern (see sh(1)); superset of PATHNAME
SH_SUBSTRING_PATTERN = any valid portable substring processing shell pattern (see sh(1));
                       superset of PATHNAME
PARAMETER            = any valid portable shell variable name except that [0-9] may occur
                       the beginning
PATHNAME             = any valid filename, directory name, relative or absolute pathname
                       excluding the characters NUL and NL
 *)

spec                 = { op_flag, } op_unary, "=", op_spec, "\n", { spec } ;
                     | { op_flag, } op_binary, op_spec, "=" op_spec, "\n", { spec } ;
                     | "#" COMMENT ;
op_unary             = "-" | "/" | "t" ;
op_binary            = ":" | "!" | "@" | "+" | "g" | "m" | "o" | "T" ;
op_flag              = "?" ;
op_spec              = pattern_spec | PATHNAME | expr_spec | op_spec ;

pattern_spec         = "%<", SH_GLOB_PATTERN, ">" ;

expr_spec            = "%[", expr, { sexpr_spec }, "%]" ;
expr                 = [ "@" ], "0" .. "9" | "DNAME" | "FNAME" | "ITEM" | PARAMETER ;

sexpr_spec           = sexpr_op_unary, SH_SUBSTRING_PATTERN, { sexpr } ;
sexpr_op_unary       = "##" | "#" | "%%" | "%" ;

Single "=" characters in spec, the "%<" and "%[" character sequences in pattern_spec and expr_spec, resp., and the sexpr_op_unary as well as sexpr_op_binary characters or character sequences may be escaped with a single backslash ("\".) SH_SUBSTRING_PATTERN differs from SH_GLOB_PATTERN solely in that any of sexpr_op_unary and sexpr_op_binary occuring at the beginning of or in the former must be escaped with a single backslash ("\",) e.g. "#\#pattern" and "%\%pattern", etc. and "#pat\%ern" and ``%patt#ern", etc., resp.

Named parameters (PARAMETER) are supplied via the -p name=value argument to rtl_install(), whereas numbered parameters are for internal usage only; the "DNAME", "FNAME", and "ITEM" parameters lazily evaluate to the directory name, file (aka base) name, and full pathname of the current item being processed relative to a specification with a pattern in it.

The following parameters are defined by default during install_files:

Name	Value
_builddir	${PKG_BUILD_DIR}
_destdir	${PKG_BASE_DIR}/${PKG_DESTDIR}
_destdir_host	${PKG_BASE_DIR}/${PKG_DESTDIR_HOST}
_files	${MIDIPIX_BUILD_PWD}/files/${PKG_NAME}
_name	${PKG_NAME}
_prefix	${PKG_PREFIX}
_prefix_host	${PREFIX}
_prefix_native	${PREFIX_NATIVE}
_subdir	${PKG_BASE_DIR}/${PKG_SUBDIR}
_target	${PKG_TARGET}
_version	${PKG_VERSION:-}
_workdir	${BUILD_WORKDIR}

The following operation flags are defined:

Flag	Description
?	Continue on soft failure

The following operations are defined:

Operation	Arity	Description
-	Unary	Remove directories and/or files
/	Unary	Create directories or trees thereof
t	Unary	touch(1) files and/or directories
:	Binary	Copy directories and/or files
!	Binary	Move/rename directories and/or files
@	Binary	Create/update symbolic links
+	Binary	Copy directories and/or files if newer and follow symbolic links
g	Binary	Set group owner of files and/or directories
m	Binary	Set mode bits of files and/or directories
o	Binary	Set user and/or group owner of files and/or directories
T	Binary	touch(1) files and/or directories with timestamp

The following expression modifiers are defined:

Modifier	Description
@	Recursively reevaluate after substituting

The following subexpression operators are defined:

Operation	Arity	Description
##	Unary	Remove largest prefix from left-hand side
#	Unary	Remove prefix from left-hand side
%%	Unary	Remove largest postfix from right-hand side
%	Unary	Remove postfix from right-hand side

#
# Examples:
# 

#
# Create directory %[_minipix]/bin and copy all files
# in %[_minipix_dist]/bin/ to %[_minipix]/bin/ with
# identical file names.
/=%[_minipix]/bin
?%[_minipix_dist]/bin/%<*>=%[_minipix]/bin/%[FNAME]

#
# Rename all files in share/info/ matching *.info to
# their filenames with the `.info' postfix removed and
# `-2.64.info' appended and all files in share/man/man1/
# matching *.1 with the `.1' postfix removed and -2.64.1
# appended.
!share/info/%<*.info>=share/info/%[FNAME%.info]-2.64.info
!share/man/man1/%<*.1>=share/man/man1/%[FNAME%.1]-2.64.1

#
# Create/update symbolic links named include/ffi.h and
# include/ffitarget.h with ../lib/libffi-3.2.1/include/ffi.h
# and ../lib/libffi-3.2.1/include/ffitarget.h as targets, resp.
@../lib/libffi-3.2.1/include/ffi.h=include/ffi.h
@../lib/libffi-3.2.1/include/ffitarget.h=include/ffitarget.h

#
# Manual invocation:
PKG_INSTALL_FILES_V2="
        [ ... ]
";
rtl_install                                                     \
                -p "_builddir=${PKG_BASE_DIR}/${PKG_BUILD_DIR}" \
                -p "_minipix=${PREFIX_MINIPIX##*/}"             \
                -p "_minipix_dist=${PREFIX}/minipix_dist"       \
                -p "_native=${PREFIX_NATIVE##*/}"               \
                -p "_subdir=${PKG_BASE_DIR}/${PKG_SUBDIR}"      \
                -p "_target=${PKG_TARGET}"                      \
                -n -- "${PREFIX}"                               \
                "${PKG_INSTALL_FILES_V2}"; then
        return 1;
fi;

#
# Usage screen:
usage: rtl_install [-i] [-I ifs] [-n] [-p name=val] [-v] prefix spec_list
       -i...........: continue on soft errors
       -I ifs.......: process spec_list with ifs instead of NL
       -n...........: perform dry run
       -p name=val..: set named parameter
       -v...........: increase verbosity
       prefix.......: pathname prefix
       spec_list....: ifs-separated list of specs

Back to top

4.4. Package variables

The following variables are package-specific and receive their value from either top-level defaults defined in vars.env.d/*.env, build group-specific defaults from the build group the package pertains to and defined in its corresponding file beneath groups.d/ or groups.d/[0-9][0-9][0-9].<group name>.d/, or package-specific overrides defined either in the latter and/or in its corresponding file beneath vars/, with one of the following prefixes:

Variable name prefix
DEFAULT
DEFAULT_${BUILD_TYPE}
DEFAULT_${GROUP_NAME}
${GROUP_NAME}
[PKG_${RELATED_PACKAGE(S)}]
[PKG_${RELATED_PACKAGE(S)}_${BUILD_KIND}]
PKG_${NAME}
PKG_${NAME}_${BUILD_KIND}

Additionally, overrides may be specified on a per-build basis on the command- line, with each variable prefixed w/ PKG_, e.g.: ./build.sh [ ... ] PKG_ZSH_CC="/usr/bin/clang".

The minimum set of package variables that must be provided is SHA256SUM, URL, VERSION and/or URLS_GIT, respectively.

4.4.1 Package variable types

Type definition	Description
DirName(Abs)	Absolute pathname to directory
DirName(Rel)	Relative pathname to director
DirName(Unit)	Single non-{absolute,relative} directory nam
DirName	Absolute or relative pathname to director
CmdName	Absolute or relative pathname to comman
FileName(Abs)	Absolute pathname to file
FileName(Rel)	Relative pathname to file
FileName(Unit)	Single non-{absolute,relative} file name
FileName	Absolute or relative pathname to file
Flag(,)	Boolean flag of type , e.g. Flag(Boolean) (true, false,) Flag(UInt) (0, 1,) Flag(ExitStatus) (>=1, 0) with default or auto
FlagLine	String of {SP,VT}-separated flags, arguments, options, etc. pp. to a command
List([,<sep|type>..])	<sep>-separated list, optionally recursively and/or sub-typing, e.g.: List(:,=,String) and "name=value:name2=value"
PkgName	Single name of package
PkgRelation	Single, possibly parametrised, package-package relation; see section 3.5
PkgVersion	Single version of package
Set()	Set of alternatives of , e.g. one of cross, host, native
String	Semantically generic string
URL	URL in standard format; see section 3.4
URL(Git)	Git URL in the format [subdir=]URL[@branch]; see section 3.4

4.4.2 Package variables

Package variable name	Type	Description
AR	CmdName	Toolchain library archive editor ar(1)
AUTOCONF_CONFIG_GUESS	String	Either of copy (copy config.guess from etc/config.guess) or keep; defaults to copy
BASE_DIR	DirName(Abs)	Package build root directory beneath ${BUILD_WORKDIR}
BUILD_DIR	DirName(Unit)	Package build directory beneath ${PKG_BASE_DIR}
BUILD_STEPS_DISABLE	List( )	Build steps to disable during package build
BUILD_TYPE	Set(String)	cross: Cross-compiled toolchain, host: host, native: cross-compiled package
CC	FileName	Toolchain C compiler cc(1)
CCLD	FileName	Toolchain C compiler-qua-linker cc(1)
CFLAGS_BUILD_EXTRA	FlagLine	Additional C compiler flags during package make(1) build
CFLAGS_BUILD	FlagLine	C compiler flags during package make(1) build
CFLAGS_CONFIGURE_EXTRA	FlagLine	Additional C compiler flags during package (GNU autotools in implementation and/or interface) configuration
CFLAGS_CONFIGURE	FlagLine	C compiler flags during package (GNU autotools in implementation and/or interface) configuration
CMAKE_ARGS_EXTRA	FlagLine	Additional arguments to cmake(1)
CMAKE_ARGS	FlagLine	Arguments to cmake(1)
CMAKE	CmdName	cmake(1) executable
CMAKE_LISTFILE	FileName	cmake(1) listfile
CONFIG_CACHE_EXTRA	List(\n)	Additional GNU autotools configuration cache variables
CONFIG_CACHE	List(\n)	GNU autotools configuration cache variables
CONFIG_CACHE_LOCAL	List(\n)	Additional GNU autotools configuration cache variables
CONFIGURE_ARGS	FlagLine	Arguments to package (GNU autotools in implementation and/or interface) configuration script
CONFIGURE_ARGS_EXTRA	FlagLine	Additional arguments to package (GNU autotools in implementation and/or interface) configuration script
CONFIGURE_ARGS_LIST	List(:)	Arguments to package (GNU autotools in implementation and/or interface) configuration script
CONFIGURE_ARGS_EXTRA_LIST	List(:)	Additional arguments to package (GNU autotools in implementation and/or interface) configuration script
CONFIGURE	CmdName	Package's (GNU autotools in implementation and/or interface) configuration script
CONFIGURE_TYPE	String	Either of autotools (GNU autotools or similar) or sofort or cmake (CMake)
CPPFLAGS_CONFIGURE_EXTRA	FlagLine	Additional C preprocessor flags during package (GNU autotools in implementation and/or interface) configuration
CXX	CmdName	Toolchain C++ compiler c++(1)
CXXFLAGS_CONFIGURE_EXTRA	FlagLine	Additional C++ compiler flags during package (GNU autotools in implementation and/or interface) configuration
CXXFLAGS_CONFIGURE	FlagLine	C++ compiler flags during package (GNU autotools in implementation and/or interface) configuration
DEPENDS	List( )	Mandatory package-package dependencies
DESTDIR	DirName(Unit)	Package installation destination directory beneath ${PKG_BASE_DIR}
DESTDIR_HOST	DirName(Unit)	Optional host package installation destination directory beneath ${PKG_BASE_DIR}
DISABLED	Flag(UInt,0)	Disable package
ENV_VARS_EXTRA	List(:,=)	Name-value pairs of environment variables to set during package build
FNAME	FileName(Unit)	Filename of package archive file
FORCE_AUTORECONF	Flag(UInt,0)	Forcibly run autoreconf -fiv prior to package (GNU autotools in implementation and/or interface) configuration
GITROOT	URL	midipix packages Git URL prefix
INHERIT_FROM	String	Inherit variables from named package
INSTALL_FILES_DESTDIR_EXTRA	List( )	Additional files to initialise the package installation destination directory beneath ${PKG_BASE_DIR} with
INSTALL_FILES_DESTDIR	List( )	Files to initialise the package installation destination directory beneath ${PKG_BASE_DIR} with
INSTALL_FILES	List( )	Files to manually install into the package installation destination directory beneath ${PKG_BASE_DIR}
INSTALL_FILES_V2	List( )	Files to manually install into the package installation destination directory beneath ${PKG_BASE_DIR}
INSTALL_TARGET_EXTRA	String	Additional name of package build make(1) installation target
INSTALL_TARGET	String	Name of package build make(1) installation target
IN_TREE	Flag(UInt,auto)	Build package in-tree within ${PKG_SUBDIR}
LDFLAGS_BUILD_EXTRA	FlagLine	Additional linker flags during package make(1) build
LDFLAGS_CONFIGURE_EXTRA	FlagLine	Additional linker flags during package (GNU autotools in implementation and/or interface) configuration
LDFLAGS_CONFIGURE	FlagLine	Linker flags during package (GNU autotools in implementation and/or interface) configuration
LIBTOOL	CmdName	libtool(1) implementation (defaults to slibtool)
MAKE	CmdLine	Command line of make(1)
MAKEFLAGS_BUILD	FlagLine	make(1) flags during package make(1) build; subject to field splitting w/ :
MAKEFLAGS_BUILD_EXTRA	FlagLine	Additional make(1) flags during package make(1) build; subject to field splitting w/ :
MAKEFLAGS_BUILD_LIST	List(:)	make(1) flags during package make(1) build; subject to field splitting w/ :
MAKEFLAGS_BUILD_EXTRA_LIST	List(:)	Additional make(1) flags during package make(1) build; subject to field splitting w/ :
MAKEFLAGS_INSTALL	FlagLine	make(1) flags during package make(1) installation; subject to field splitting w/ :
MAKEFLAGS_INSTALL_EXTRA	FlagLine	make(1) flags during package make(1) installation; subject to field splitting w/ :
MAKEFLAGS_INSTALL_LIST	List(:)	make(1) flags during package make(1) installation; subject to field splitting w/ :
MAKEFLAGS_INSTALL_EXTRA_LIST	List(:)	make(1) flags during package make(1) installation; subject to field splitting w/ :
MAKEFLAGS_LOADAVG	FlagLine	make(1) load average limit (e.g. -l load) flag
MAKEFLAGS_PARALLELISE	FlagLine	make(1) parallelisation (e.g. -j jobs) flag
MAKEFLAGS_VERBOSITY	String	Variable-value pair to pass to make(1) in order to force echo-back of command lines prior to execution
MAKE_INSTALL_VNAME	String	Variable name of make(1) installation destination directory variable during package make(1) installation
MAKE_SUBDIRS	List( )	make(1) subdirectories to exclusively build
MIRRORS_GIT	List( )	Package Git repository mirror base URLs to attempt cloning from; cf. pkgtool.sh -m <dname>
MIRRORS	List( )	Package archive mirror base URLs to attempt downloading from; cf. pkgtool.sh -m <dname>
NO_CLEAN_BASE_DIR	Flag(UInt,0)	Inhibit cleaning of package build root directory beneath ${BUILD_WORKDIR}
NO_CLEAN	Flag(UInt,0)	Inhibit cleaning of package build directory beneath ${PKG_BASE_DIR} pre-finish
NO_LOG_VARS	Flag(UInt,0)	Inhibit logging of build & package variables pre-package build
NO_PURGE_LA_FILES	Flag(UInt,0)	Inhibit purging of .la files
PATCHES_EXTRA	List( )	Additional patches to apply
PKG_CONFIG	CmdName	pkg-config(1) implementation
PKG_CONFIG_LIBDIR	DirName	pkg-config(1) search directory
PKGLIST_DISABLE	Flag(UInt,0)	Inhibit inclusion into ${PREFIX}/pkglist.${PKG_BUILD_TYPE}
PREFIX	DirName(Abs)	Top-level installation directory and package search path
PYTHON	CmdName	Python >=3.x interpreter
RANLIB	CmdName	Toolchain library archive index generator ranlib(1)
RELATES	Set(PkgRelation)	Package-package relationships
RPM_DISABLE	Flag(UInt,0)	Inhibit creation of RPM archive
SHA256SUM	String	SHA-256 message digest of package archive
SOFORT_NATIVE_CC	FileName	sofort variable during native build: Toolchain C compiler cc(1)
SOFORT_NATIVE_CFLAGS_EXTRA	FlagLine	sofort variable during native build: Additional C compiler flags during package (GNU autotools or similar) configuration
SOFORT_NATIVE_CFLAGS	FlagLine	sofort variable during native build: C compiler flags during package (GNU autotools or similar) configuration
SOFORT_NATIVE_CXXFLAGS_EXTRA	FlagLine	sofort variable during native build: Additional list of C++ compiler flags during package (GNU autotools or similar) configuration
SOFORT_NATIVE_CXXFLAGS	FlagLine	sofort variable during native build: List of C++ compiler flags during package (GNU autotools or similar) configuration
SOFORT_NATIVE_CXX	FlagLine	sofort variable during native build: Command- or pathname of toolchain C++ compiler c++(1)
SOFORT_NATIVE_LDFLAGS_EXTRA	FlagLine	sofort variable during native build: Additional linker flags during package (GNU autotools or similar) configuration
SOFORT_NATIVE_LDFLAGS	FlagLine	sofort variable during native build: Linker flags during package (GNU autotools or similar) configuration
SOFORT_NATIVE_LD	FileName	sofort variable during native build: Command- or pathname of toolchain C compiler cc(1)
SUBDIR	DirName(Rel)	Extracted archive or git-{clone,pull}(1)'d directory
TARGET	String	Dash-separated {build,host,target} triplet
URL	List( ,URL)	URL to package archives w/ optional alternatives; see section 3.4
URLS_GIT	List( ,URL(Git))	Package Git URL(s) (format: [subdir=]URL[@branch], see section 3.4)
VARS_FILE	FileName	Optional package variables file (defaults to vars/${PKG_NAME}.vars)
VERSION	PkgVersion	Package version

Back to top

4.5. Fault-tolerant & highly optimised 3D laser show-equipped usage screen

usage: ./build.sh [-a nt32|nt64]  [-b debug|release]    [-C dir[,..]]  [-D kind[,..]]
                  [-F ipv4|ipv6|offline]    [-h|--help] [-p jobs|-P]    [-r ALL|LAST]
                  [-r [*[*[*]]]name[,..][:ALL|LAST|[^|<|<=|>|>=]step,..]]        [-R]
                  [-v] [-V [+]tag|pat[,..]]

                  [--as-needed] [--debug-minipix]  [--reset-state] [--roar]
                  [--theme theme]
                  [[=]<group[,..][ ..]>|<variable name>=<variable override>[ ..]]

        -a nt32|nt64        Selects 32-bit or 64-bit architecture; defaults to nt64.
        -b debug|release    Selects debug or release build kind; defaults to debug.
        -C dir[,..]         Clean build directory (build,) ${PREFIX} before processing build
                            scripts (prefix,) source directory (src,) and/or destination
                            directory (dest) after successful package builds.
        -D kind[,..]        Produce minimal midipix distribution directory (minipix,) RPM
                            binary packages (rpm,) and/or deployable distribution ZIP
                            archive (zipdist.) zipdist implies minipix.
        -F ipv4|ipv6|offline
                            Force IPv4 (ipv4) or IPv6 (ipv6) when downloading package
                            archives and/or Git repositories or don't download either at all
                            (offline.)
        -h|--help           Show short/full help screen, respectively.
        -p jobs|-P          Enables parallelisation at group-level, whenever applicable.
                            The maximum count of jobs defaults to the number of logical
                            processors on the host system divided by two (2.)

                            If -R is not specified and at least one (1) package fails to
                            build, all remaining package builds will be forcibly aborted.

        -r ALL|LAST         Restart all packages or the last failed package and resume
                            build, resp.
        -r [*[*[*]]]name[,..][:ALL|LAST|[^|<|<=|>|>=]step,..]
                            Restart the specified comma-separated package(s) w/ inhibition
                            of package build step state resetting completely (`ALL',) starting
                            at the resp. last successfully executed build steps (`LAST',) or the
                            specified comma-separated list of build steps, optionally subject
                            concerning package name(s) and/or build step(s) to the below modifiers:

                            Prepend name w/ `*' to automatically include dependencies, `**'
                            to forcibly rebuild all dependencies, and `***' to forcibly
                            rebuild all packages that depend on the specified package(s).

                            Prepend step w/ `^' to filter build steps with, `<' or `<='
                            to constrain build steps to below or below or equal with, resp.,
                            `>' or `>=' to constrain build steps to above or above or equal
                            with, resp.

                            Currently defined build steps are:
                            fetch_clean, fetch_download, fetch_extract, configure_clean,
                            configure_patch_pre, configure_autotools, configure_patch,
                            configure, build_clean, build, install_clean, install_subdirs,
                            install_make, install_files, install, install_rpm,
                            and clean.

                            Additionally, the following virtual steps are provided:
                            @fetch, @configure, @build, @install, @clean, and finish.

        -R                  Ignore build failures, skip printing package logs, and continue
                            building (relaxed mode.)

        -v                  Increase logging verbosity.
        -V [+]tag|pat[,..]  Enable logging for messages with tag or pattern matching tags of:
                            + (prefix)..: initialise tags with normal verbosity (implies normal) (see etc/build.theme,)
                            all.........: log everything (see etc/build.theme,)
                            clear|none..: log nothing,
                            normal......: log at normal verbosity (see etc/build.theme,)
                            verbose.....: log at increased verbosity (implies normal) (see etc/build.theme) (-v,)

                            build.......: log package build logs,
                            fileops.....: log RTL file operations,
                            install.....: log RTL installation DSL operations,
                            zipdist.....: log deployable distribution ZIP archive operations,
                            xtrace......: set xtrace during package builds,

                            fatal.......: fatal, unrecoverable errors,
                            info........: informational messages,
                            verbose.....: verbose informational messages,
                            warning.....: warning messages possibly relating to imminent fatal, unrecoverable errors,

                            build_*.....: general build messages (viz.: begin, finish, finish_time, vars,)
                            group_*.....: build group messages (viz.: begin, finish,)
                            pkg_*.......: package build messages (viz.: begin, finish, msg, skip, step, strip.)

        --as-needed         Don't build unless the midipix_build repository has received
                            new commits.
        --debug-minipix     Don't strip(1) minipix binaries to facilitate debugging minipix.
        --reset-state       Reset package build step state on exit.
        --theme theme       Set theme.

        <group>[,..][ ..]   One of: dev_packages, dist, host_deps, host_deps_rpm,
                            host_toolchain, host_tools, minipix, native_packages,
                            native_runtime, native_toolchain, native_tools.

                            Prepend w/ `=' to inhibit group-group dependency expansion.

        <variable name>=<variable override>[ ..]
                            Override build or package variable.

Back to top

4.6. pkgtool.sh

usage: ./pkgtool.sh [-a nt32|nt64] [-b debug|release] [-e|-f|-i|-m <dname> -M <dname>|-p|-r|-t]
                    [--theme theme] [-v]
                    [<variable name>=<variable override>[ ..]] name[,name..]

        -a nt32|nt64      Selects 32-bit or 64-bit architecture; defaults to nt64.
        -b debug|release  Selects debug or release build kind; defaults to debug.
        -e                Edit package group file of single named package with ${EDITOR}.
        -f                List files installed by single package.
        -i                List package variables and dependencies of named package(s).
        -m <dname>        Setup package archives mirror in <dname> and/or
        -M <dname>        Setup Git repositories mirror in <dname>
                          Specify "" or '' as <dname> to default to the defaults in
                          ${HOME}/pkgtool.vars, if present.
        -p <log_fname>    Profile last build.
        -r                List recursive reverse dependencies of single named package.
        -t                Produce tarball of package build root directory and build log
                          file for the purpose of distribution given build failure.
        -v                Increase verbosity.

        <variable name>=<variable override>[ ..]
                          Override build or package variable.

N.B. When using pkgtool.sh on a build w/ build variables (see section 4.2) overriden on the command line or via the environment, ensure that they are included in the pkgtool.sh command line, preceding the package name, or exported, respectively.

N.B. pkgtool.sh will source the ${HOME}/pkgtool.vars file, if present, on startup where the following option arguments may be set: -a nt32|nt64 by setting ARCH=..., -b debug|release by setting BUILD_KIND=..., -m <dname> by setting ARG_MIRROR_DNAME=..., and -M <dname> by setting ARG_MIRROR_DNAME_GIT=....

Back to top

4.7. Bourne shell coding rules

N.B. Input sanitisation is mandatory whenever input may form part of a parameter name, most usually when indexing with input as a key into a (pseudo-)hash, e.g. PKG_ZSH_<...input...>; failing to do so may introduce security vulnerabilities (e.g.: $(arbitrary_command) and ${arbitrary_variable} facilitating code execution and information disclosure, resp.)
Do not use this code and these coding rules if this is not possible or impractical.

(reproduced from [shrtl])

If no rationale is specified for any specific point, the rationale is avoidance of undefined behaviour and/or implicit behaviour contingent on often subtle special cases, both of which are prone to cause hard to debug or even diagnose bugs.

Shell options

1. The noglob option is set at all times except for when globbing is required, e.g.: set +o noglob; files=*; set -o noglob
2. The nounset option is set at all times; if a parameter is to be expanded that may be unset, use the ${parameter:-word} expansion format.
3. The errexit option is unset at all times except for top-level subshell code that does not engage in conditional evaluation, e.g. ([...] set -o errexit; [...]) & due to its implicit unsetting when a/any function is subject to conditional evaluation, e.g.: [...] set -o errexit; [...] if some_function; then [ ... ] fi

Quoting and brace-enclosing

4. Quoting with single quotes or double quotes is mandatory at all times except for when field splitting subsequent to parameter expansion, etc. is required, e.g.: params="a b c"; param="single parameter"; fn ${params} "${param}"
5. Enclosing parameter names in braces is mandatory at all times, e.g.: ${parameter_name123}

Checking parameter status

6. Checking for whether a parameter is set/non-empty or unset/empty is expressed with the following the idiom: [ "${parameter:+1}" = 1 ] and [ "${parameter:+1}" != 1 ]

   This is necessary to avoid the potentially costly expansion of a parameter's value when only its status of being set/non-empty or unset/empty is of concern, particularly when this is done repeatedly.

Functions

7. Functions must explicitly return either 0 or 1 at all times except for when specific return exit statuses are specified according to the function's interface contract.

8. Function names must have namespace prefixes followed by a p in the topmost namespace prefix field in private functions, e.g.: rtlp_log_do_something() { [...] }

9. The non-POSIX but extremely widely available local command must be used at at all times in functions on all function-local variables.

   This is necessary in order to avoid polluting the (global) parameter namespace.

10. Function-local variables must be lower case and prefixed with a _, a prefix comprised of the initial letters of each word in the function's name plus, in private functions, the p topmost namespace prefix field postfix, and a _, where words are separated by _ characters, e.g.: rtlp_log_do_something() { local _rplds_parameter=""; [...] } and ex_something() { local _es_parameter=""; [ ...] }

    This is necessary in order to prevent implicit conflicts between two or more functions that share a call path and would otherwise use the same variables names, such as function1() { local list="${1}"; function2 "${list}"; }; function2() { local list="${2}"; }, particularly when those functions acess and/or mutate each other's variables. Additionally, local variables are thus marked with a _ prefix and by being lower case.

eval rules

11. The following special characters must be escaped with a backslash at all times in eval expressions: <newline>, ", ', [, \, ], <backtick>, $
12. If parameter expansion is to be evaluated with respect to a parameter reference, the following idiom must be used at all times: eval [...]\${${rparameter[...]}}
13. If quoting with single quotes or double quotes is required - see 4) - or brace-enclosing - see 5) - and with respect to 11), viz. the single quotes or double quotes have been escaped with a backslash, something must be evaluated as a single field, then that field must be doubly quoted with single or double quotes, where the second set of quotes must not be escaped with a backslash, e.g.: rparameter=parameter; eval ${rparameter}="\"a b c\"". This is very rarely required.

Passing arguments

14. The fork/exec/write-read pattern where a parameter is set to the result of a command substitution expression which is executed in a subshell process, e.g.: parameter="$(function)" is prohibited at all times except when an actual external command is invoked, e.g. sort(1) or sed(1).

    This is necessary due to the very significant cost of the mentioned pattern, particularly concerning primitive e.g. list or string processing functions with high contention.

15. If a function is to return, produce, evaluate to, etc. an arbitrary value apart from the exit status, it shall do so by receiving references to the target variables in the callers' scope from the caller prefixed with a single $ character, e.g. function \$parameter and function() { local _fn_rparameter="${1#\$}"; [..]; } which are then set with eval expressions: function() { local _fn_rparameter="${1#\$}"; [...]; eval ${_fn_rparameter}=\'a b c\'; }; Refer to 11)-13) for the rules concerning eval.

    This is necessary due to 14) as well as the absence of any other calling convention other than using implicit global variables, e.g.: function1() { VARIABLE=; function2; }; function2() { VARIABLE=1; }

Back to top

5. References

• Sun, 25 Apr 2016 09:04:08 +0000 [1]musl FAQ
• Wed, 04 Mar 2020 13:36:19 +0000 [2]midipix - what is midipix, and how is it different?
• Wed, 29 Apr 2020 23:33:34 +0100 [3]User Rights Assignment (Windows 10) - Windows security | Microsoft Docs
• Wed, 29 Apr 2020 23:33:50 +0100 [4]Windows Vista Application Development Requirements for User Account Control Compatibility | Microsoft Docs

Back to top