Small sample program explaining how to use execl command

.gitignore

pyinbash.sh
py3-script.py
pyscript.py
scripts
scripts/*
execl-example
execl-example.dSYM/

execl-example.c

#include<stdio.h>
#include<errno.h>
#include<stdlib.h>
#include<strings.h>
#include<unistd.h>

#define BASH_EXEC "/bin/bash"
#define LS_EXEC "/bin/ls"

#define BSIZE 50

int main(int argc, char* argv[]){
	printf("%d", argc);

    if(argc < 2) {
	    //if we do not have path in our program arguments print help message and exit
	    printf("Usage: execl-example PATH \n eg. execl-example /usr/bin\n");
	    fflush(stdout);
	    return 0;
    }

    //this is a temp buffer used that will be used to build the argument
    char buffer[BSIZE];

    //get the buffer to be all NULLs
    bzero(buffer, BSIZE);

    //build the argument "ls -l /path/to/list/folders" and store it in buffer
    sprintf(buffer, "%s -l %s", LS_EXEC, argv[1]);
    //printf("buffer: %s\n", buffer);
    //build the argument vector

    //execute the command
    if(execl(BASH_EXEC, BASH_EXEC, "-c", buffer, NULL) < 0){
	    printf("Something terrible happended!");
	    return 1;
    }

    return 0;
}

GNUmakefile

SHELL := /bin/bash

PWD 									?= pwd_unknown

THIS_FILE								:= $(lastword $(MAKEFILE_LIST))
export THIS_FILE
TIME									:= $(shell date +%s)
export TIME

ARCH                                    :=$(shell uname -m)
export ARCH
ifeq ($(ARCH),x86_64)
TRIPLET                                 :=x86_64-linux-gnu
export TRIPLET
endif
ifeq ($(ARCH),arm64)
TRIPLET                                 :=aarch64-linux-gnu
export TRIPLET
endif

GCC                                     :=$(shell which gcc)
CLANG                                   :=$(shell which clang)
export GCC
export CLANG

ifeq ($(user),)
HOST_USER								:= root
HOST_UID								:= $(strip $(if $(uid),$(uid),0))
else
HOST_USER								:=  $(strip $(if $(USER),$(USER),nodummy))
HOST_UID								:=  $(strip $(if $(shell id -u),$(shell id -u),4000))
endif
export HOST_USER
export HOST_UID

PYTHON                                  := $(shell which python)
export PYTHON
PYTHON2                                 := $(shell which python2)
export PYTHON2
PYTHON3                                 := $(shell which python3)
export PYTHON3

PIP                                     := $(shell which pip)
export PIP
PIP2                                    := $(shell which pip2)
export PIP2
PIP3                                    := $(shell which pip3)
export PIP3

python_version_full := $(wordlist 2,4,$(subst ., ,$(shell python3 --version 2>&1)))
python_version_major := $(word 1,${python_version_full})
python_version_minor := $(word 2,${python_version_full})
python_version_patch := $(word 3,${python_version_full})

my_cmd.python.3 := $(PYTHON3) some_script.py3
my_cmd := ${my_cmd.python.${python_version_major}}

PYTHON_VERSION                         := ${python_version_major}.${python_version_minor}.${python_version_patch}
PYTHON_VERSION_MAJOR                   := ${python_version_major}
PYTHON_VERSION_MINOR                   := ${python_version_minor}

export python_version_major
export python_version_minor
export python_version_patch
export PYTHON_VERSION

#PROJECT_NAME defaults to name of the current directory.
ifeq ($(project),)
PROJECT_NAME							:= $(notdir $(PWD))
else
PROJECT_NAME							:= $(project)
endif
export PROJECT_NAME

#GIT CONFIG
GIT_USER_NAME							:= $(shell git config user.name)
export GIT_USER_NAME
GIT_USER_EMAIL							:= $(shell git config user.email)
export GIT_USER_EMAIL
GIT_SERVER								:= https://github.com
export GIT_SERVER

GIT_REPO_NAME							:= $(PROJECT_NAME)
export GIT_REPO_NAME

#Usage
#make package-all profile=rsafier
#make package-all profile=asherp
#note on GH_TOKEN.txt file below
ifeq ($(profile),)
GIT_PROFILE								:= $(GIT_USER_NAME)
ifeq ($(GIT_REPO_ORIGIN),[email protected]:PLEBNET_PLAYGROUND/plebnet-playground-docker.dev.git)
GIT_PROFILE								:= PLEBNET-PLAYGROUND
endif
ifeq ($(GIT_REPO_ORIGIN),https://github.com/PLEBNET_PLAYGROUND/plebnet-playground-docker.dev.git)
GIT_PROFILE								:= PLEBNET-PLAYGROUND
endif
else
GIT_PROFILE								:= $(profile)
endif
export GIT_PROFILE

GIT_BRANCH								:= $(shell git rev-parse --abbrev-ref HEAD)
export GIT_BRANCH
GIT_HASH								:= $(shell git rev-parse --short HEAD || false)
export GIT_HASH
GIT_PREVIOUS_HASH						:= $(shell git rev-parse --short HEAD^1 || false)
export GIT_PREVIOUS_HASH
GIT_REPO_ORIGIN							:= $(shell git remote get-url origin || false)
export GIT_REPO_ORIGIN
GIT_REPO_PATH							:= $(PWD)
export GIT_REPO_PATH

ifeq ($(nocache),true)
NOCACHE					     			:= --no-cache
#Force parallel build when --no-cache to speed up build
PARALLEL                                := --parallel
else
NOCACHE						    		:=
PARALLEL                                :=
endif
ifeq ($(parallel),true)
PARALLEL                                := --parallel
endif
ifeq ($(para),true)
PARALLEL                                := --parallel
endif
export NOCACHE
export PARALLEL

ifeq ($(verbose),true)
VERBOSE									:= --verbose
else
VERBOSE									:=
endif
export VERBOSE

-:
#NOTE: 2 hashes are detected as 1st column output with color
	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?##/ {printf "\033[36m%-15s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST)

.PHONY: help
help:## 	print verbose help
	@echo 'make [COMMAND] [EXTRA_ARGUMENTS]	'
	@echo ''
	@echo 'make '
	@echo '	 make all                        install and run playground and cluster'
	@echo '	 make help                       print help'
	@echo '	 make report                     print environment variables'
	@echo '	                                 nocache=true verbose=true'
	@echo ''
	@echo '	[DEV ENVIRONMENT]:	'
	@echo ''
	@echo '	 make signin profile=gh-user     ~/GH_TOKEN.txt required from github.com'
	@echo '	 make build'
	@echo '	 make package-all'
	@echo ''
	@echo '	[EXAMPLES]:'
	@echo ''
	@echo '	make run nocache=true verbose=true'
	@echo ''
	@echo '	make init && play help'
	@echo ''
	@sed -n 's/^# //p' ${MAKEFILE_LIST} | column -t -s ':' |  sed -e 's/^/# /'
	@sed -n 's/^## //p' ${MAKEFILE_LIST} | column -t -s ':' |  sed -e 's/^/## /'
	@sed -n 's/^### //p' ${MAKEFILE_LIST} | column -t -s ':' |  sed -e 's/^/### /'

.PHONY: report
report:## 	print environment arguments
	@echo ''
	@echo '	[ARGUMENTS]	'
	@echo '      args:'
	@echo '        - THIS_FILE=${THIS_FILE}'
	@echo '        - TIME=${TIME}'
	@echo '        - ARCH=${ARCH}'
	@echo '        - TRIPLET=${TRIPLET}'
	@echo '        - PROJECT_NAME=${PROJECT_NAME}'
	@echo '        - HOME=${HOME}'
	@echo '        - PWD=${PWD}'
	@echo '        - PYTHON=${PYTHON}'
	@echo '        - PYTHON3=${PYTHON3}'
	@echo '        - PYTHON_VERSION=${PYTHON_VERSION}'
	@echo '        - PYTHON_VERSION_MAJOR=${PYTHON_VERSION_MAJOR}'
	@echo '        - PYTHON_VERSION_MINOR=${PYTHON_VERSION_MINOR}'
	@echo '        - PIP=${PIP}'
	@echo '        - PIP3=${PIP3}'
	@echo '        - PACKAGE_PREFIX=${PACKAGE_PREFIX}'
	@echo '        - HOST_USER=${HOST_USER}'
	@echo '        - HOST_UID=${HOST_UID}'
	@echo '        - SERVICE_TARGET=${SERVICE_TARGET}'
	@echo '        - DOCKER_COMPOSE=${DOCKER_COMPOSE}'
	@echo '        - GIT_USER_NAME=${GIT_USER_NAME}'
	@echo '        - GIT_USER_EMAIL=${GIT_USER_EMAIL}'
	@echo '        - GIT_SERVER=${GIT_SERVER}'
	@echo '        - GIT_PROFILE=${GIT_PROFILE}'
	@echo '        - GIT_BRANCH=${GIT_BRANCH}'
	@echo '        - GIT_HASH=${GIT_HASH}'
	@echo '        - GIT_PREVIOUS_HASH=${GIT_PREVIOUS_HASH}'
	@echo '        - GIT_REPO_ORIGIN=${GIT_REPO_ORIGIN}'
	@echo '        - GIT_REPO_NAME=${GIT_REPO_NAME}'
	@echo '        - GIT_REPO_PATH=${GIT_REPO_PATH}'
	@echo '        - NOCACHE=${NOCACHE}'
	@echo '        - VERBOSE=${VERBOSE}'
	@echo '        - PASSWORD=${PASSWORD}'
	@echo '        - CMD_ARGUMENTS=${CMD_ARGUMENTS}'

#######################

ORIGIN_DIR:=$(PWD)
MACOS_TARGET_DIR:=/var/root/$(PROJECT_NAME)
LINUX_TARGET_DIR:=/root/$(PROJECT_NAME)
export ORIGIN_DIR
export TARGET_DIR

.PHONY: all venv test-venv init
all: init execl-example## 	all
execl-example:## 	
	$(GCC) -g execl-example.c -o execl-example
venv:## 	create python3 virtualenv .venv
	test -d .venv || $(PYTHON3) -m virtualenv .venv
	( \
	   source .venv/bin/activate; pip install -r requirements.txt; \
	);
	@echo "To activate (venv)"
	@echo "try:"
	@echo ". .venv/bin/activate"
	@echo "or:"
	@echo "make test-venv"
	$(GCC) -g execl-example.c -o execl-example
test-venv:## 	test virutalenv .venv
	# insert test commands here
	test -d .venv || $(PYTHON3) -m virtualenv .venv
	( \
	   source .venv/bin/activate; pip install -r requirements.txt; \
	);
.PHONY: init
init: venv## 	basic setup

ifneq ($(shell id -u),0)
	@echo
	@echo $(shell id -u -n) 'try:'
	@echo 'make super'
	@echo 'If permissions issue...'
	@echo
endif

	git config --global --add safe.directory $(PWD)

	$(PYTHON3) -m pip install --upgrade pip 2>/dev/null
	$(PYTHON3) -m pip install -q -r requirements.txt 2>/dev/null

	mkdir -p scripts
	@./pyinbash.sh
	install -v $(PWD)/pyinbash.sh $(PWD)/scripts/
	chown -R $(shell id -u) *                 || echo
	bash -c "scripts/pyinbash.sh"
	install -v $(PWD)/py3-script.py $(PWD)/scripts/

	pushd $(PWD)/scripts > /dev/null; for string in *; do sudo chmod -R o+rwx /usr/local/bin/$$string; done; popd  2>/dev/null || echo
	pushd $(PWD)/scripts > /dev/null; for string in *; do install $$string /usr/local/bin/$$string; done; popd  2>/dev/null || echo

#######################
.PHONY: docs
docs: init
	@echo "Use 'make docs nocache=true' to force docs rebuild..."

	echo "## MAKE COMMAND" >> MAKE.md
	echo '```' > MAKE.md
	make help >> MAKE.md
	echo '```' >> MAKE.md

#######################
.PHONY: push
push:
	@echo push
	git checkout -b $(TIME)/$(GIT_PREVIOUS_HASH)/$(GIT_HASH)
	git push --set-upstream origin $(TIME)/$(GIT_PREVIOUS_HASH)/$(GIT_HASH)
	git add docs
	git commit --amend --no-edit --allow-empty || echo failed to commit --amend --no-edit
	git push -f origin $(TIME)/$(GIT_PREVIOUS_HASH)/$(GIT_HASH):$(TIME)/$(GIT_PREVIOUS_HASH)/$(GIT_HASH)

SIGNIN=randymcmillan
export SIGNIN

.PHONY: signin package-docker package-all
signin:
	bash -c 'cat ~/GH_TOKEN.txt | docker login ghcr.io -u $(GIT_PROFILE) --password-stdin'
#Place a file named GH_TOKEN.txt in your $HOME - create in https://github.com/settings/tokens (Personal access tokens)

requirements.txt