Update README.md

* Add environment.c

5 files changed, 116 insertions, 3 deletions

diff --git a/README.md b/README.md
index 69d92ea..dd59c04 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,7 @@ _TODO_
 ## Usage
 
 ```bash
-$ ./spm --help
+$ spm --help
 usage: spm [-hVvBIrLS]
   -h,  --help     show this help message
   -V,  --version  show version
@@ -81,6 +81,37 @@ usage: spm [-hVvBIrLS]
   -S,  --search   search for a package
 ```
 
+### Example
+
+#### Install Python
+```bash
+$ spm --root ~/spmenv123 --install "python" # [...]
+```
+
+#### Export environment variables
+
+```bash
+$ export PATH="~/spmenv123/bin:$PATH"
+$ export MANPATH="~/spmenv123/share/man:$MANPATH"
+$ hash -r  # or "rehash" if your shell supports it
+```
+
+#### Use Python
+
+```bash
+$ which python
+/home/example/spmenv123/bin/python
+$ which pip
+/home/example/spmenv123/bin/pip
+$ which git
+/home/example/spmenv123/bin/git
+
+$ python -m venv ~/spmenv123/venv
+$ source ~/spmenv123/venv/bin/activate
+$ pip install https://github.com/spacetelescope/jwst.git#egg=jwst
+# ... do work
+```
+
 ## Building SPM Packages
 
 _TODO_
diff --git a/include/spm.h b/include/spm.h
index eb6b95f..a8a4ab7 100644
--- a/include/spm.h
+++ b/include/spm.h
@@ -261,4 +261,9 @@ int file_is_binexec(const char *filename);
 // internal_cmd.c
 int internal_cmd(int argc, char **argv);
 
+// environment.c
+char **runtime_copy(char **env);
+void runtime_export(char **env);
+void runtime_free(char **env);
+
 #endif //SPM_SPM_H
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8981122..0d53e9b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -3,7 +3,7 @@ include_directories(
 	${CMAKE_BINARY_DIR}/include
 )
 
-add_executable(spm spm.c config.c compat.c deps.c fs.c rpath.c find.c shell.c archive.c strings.c relocation.c install.c config_global.c manifest.c checksum.c extern/url.c version_spec.c spm_build.c mime.c internal_cmd.c)
+add_executable(spm spm.c config.c compat.c deps.c fs.c rpath.c find.c shell.c archive.c strings.c relocation.c install.c config_global.c manifest.c checksum.c extern/url.c version_spec.c spm_build.c mime.c internal_cmd.c environment.c)
 target_link_libraries(spm rt crypto ssl curl)
 
 if(MSVC)
diff --git a/src/environment.c b/src/environment.c
new file mode 100644
index 0000000..d338e4a
--- /dev/null
+++ b/src/environment.c
@@ -0,0 +1,77 @@
+/**
+ * @file environment.c
+ */
+#include "spm.h"
+
+/**
+ *
+ * @param env
+ */
+void runtime_export(char **env) {
+    char *borne[] = {
+            "bash",
+            "dash",
+            "zsh",
+            NULL,
+    };
+    char *unborne[] = {
+            "csh"
+            "tcsh",
+            NULL,
+    };
+
+    char output[BUFSIZ];
+    char export_command[7]; // export=6 and setenv=6... convenient
+    char *_sh = getenv("SHELL");
+    char *sh = basename(_sh);
+    if (sh == NULL) {
+        fprintf(stderr, "echo SHELL environment variable is not defined");
+        exit(1);
+    }
+
+    for (size_t i = 0; borne[i] != NULL; i++) {
+        if (strcmp(sh, borne[i]) == 0) {
+            strcpy(export_command, "export");
+            break;
+        }
+    }
+    for (size_t i = 0; unborne[i] != NULL; i++) {
+        if (strcmp(sh, unborne[i]) == 0) {
+            strcpy(export_command, "setenv");
+            break;
+        }
+    }
+
+    for (size_t i = 0; env[i] != NULL; i++) {
+        char **pair = split(env[i], "=");
+        sprintf(output, "%s %s=\"%s\"", export_command, pair[0], pair[1] ? pair[1] : "");
+        puts(output);
+        split_free(pair);
+    }
+}
+
+/**
+ *
+ * @param env
+ * @return
+ */
+char **runtime_copy(char **env) {
+    char **envp = NULL;
+    size_t env_count;
+    for (env_count = 0; env[env_count] != NULL; env_count++);
+
+    envp = (char **)calloc(env_count + 1, sizeof(char *));
+    for (size_t i = 0; i < env_count; i++) {
+        size_t len = strlen(env[i]);
+        envp[i] = (char *)calloc(len + 1, sizeof(char));
+        memcpy(envp[i], env[i], len);
+    }
+    return envp;
+}
+
+void runtime_free(char **env) {
+    for (size_t i = 0; env[i] != NULL; i++) {
+        free(env[i]);
+    }
+    free(env);
+}
\ No newline at end of file
diff --git a/src/spm.c b/src/spm.c
index 5759688..09538eb 100644
--- a/src/spm.c
+++ b/src/spm.c
@@ -24,7 +24,7 @@ void usage(const char *program_name) {
            , program_name);
 }
 
-int main(int argc, char *argv[]) {
+int main(int argc, char *argv[], char *arge[]) {
     char program_name[strlen(argv[0]) + 1];
     memset(program_name, '\0', sizeof(program_name) + 1);
     strcpy(program_name, basename(argv[0]));