env: Add env.py

Author: Expertcoderz

userland/utilities/env.py

@@ -0,0 +1,98 @@
+import os
+import shlex
+import sys
+
+from .. import core
+
+
+parser = core.create_parser(
+    usage=("%prog [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]",),
+)
+parser.disable_interspersed_args()
+
+parser.add_option(
+    "-a",
+    "--argv0",
+    metavar="ARG",
+    help="pass ARG as zeroth argument instead of COMMAND",
+)
+parser.add_option(
+    "-i",
+    "--ignore-environment",
+    action="store_true",
+    help="start with empty environment",
+)
+parser.add_option(
+    "-u",
+    "--unset",
+    action="append",
+    metavar="NAME",
+    help="remove variable NAME from the environment",
+)
+parser.add_option(
+    "-0",
+    "--null",
+    action="store_true",
+    help="terminate outputs with NUL instead of newline",
+)
+parser.add_option(
+    "-C",
+    "--chdir",
+    metavar="DIR",
+    help="change working directory to DIR",
+)
+parser.add_option(
+    "-S",
+    "--split-string",
+    metavar="STRING",
+    help="split STRING into separate arguments",
+)
+
+
+@core.command(parser)
+def python_userland_env(opts, args):
+    if args and args[0] == "-":
+        opts.ignore_environment = True
+        del args[0]
+
+    if opts.ignore_environment:
+        env = {}
+    elif opts.unset:
+        env = {
+            name: value for name, value in os.environ.items() if name not in opts.unset
+        }
+    else:
+        env = os.environ.copy()
+
+    prog_args = []
+
+    parsing_decls = True
+    for arg in args:
+        if parsing_decls and (eq_pos := arg.find("=")) >= 0:
+            env[arg[:eq_pos]] = arg[eq_pos + 1 :]
+        else:
+            prog_args.append(arg)
+            parsing_decls = False
+
+    if opts.split_string:
+        prog_args = shlex.split(opts.split_string) + prog_args
+
+    if not prog_args:
+        for name, value in env.items():
+            print(f"{name}={value}", end="\0" if opts.null else "\n")
+        return
+
+    if opts.chdir:
+        try:
+            os.chdir(opts.chdir)
+        except OSError as e:
+            print(e, file=sys.stderr)
+            return 125
+
+    prog_args.insert(1, opts.argv0 if opts.argv0 else prog_args[0])
+
+    try:
+        os.execvpe(prog_args[0], prog_args[1:], env)
+    except OSError as e:
+        print(e, file=sys.stderr)
+        return 126 if isinstance(e, FileNotFoundError) else 127