[Misc] Refactor: Improve argument handling for `conda` command (#20481)

Signed-off-by: reidliu41 <reid201711@gmail.com>

vllm/collect_env.py

@@ -96,25 +96,30 @@ DEFAULT_PIP_PATTERNS = {
 def run(command):
     """Return (return-code, stdout, stderr)."""
     shell = True if type(command) is str else False
-    p = subprocess.Popen(command,
-                         stdout=subprocess.PIPE,
-                         stderr=subprocess.PIPE,
-                         shell=shell)
-    raw_output, raw_err = p.communicate()
-    rc = p.returncode
-    if get_platform() == 'win32':
-        enc = 'oem'
-    else:
-        enc = locale.getpreferredencoding()
-    output = raw_output.decode(enc)
-    if command == 'nvidia-smi topo -m':
-        # don't remove the leading whitespace of `nvidia-smi topo -m`
-        #   because they are meaningful
-        output = output.rstrip()
-    else:
-        output = output.strip()
-    err = raw_err.decode(enc)
-    return rc, output, err.strip()
+    try:
+        p = subprocess.Popen(command,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE,
+                             shell=shell)
+        raw_output, raw_err = p.communicate()
+        rc = p.returncode
+        if get_platform() == 'win32':
+            enc = 'oem'
+        else:
+            enc = locale.getpreferredencoding()
+        output = raw_output.decode(enc)
+        if command == 'nvidia-smi topo -m':
+            # don't remove the leading whitespace of `nvidia-smi topo -m`
+            #   because they are meaningful
+            output = output.rstrip()
+        else:
+            output = output.strip()
+        err = raw_err.decode(enc)
+        return rc, output, err.strip()
+
+    except FileNotFoundError:
+        cmd_str = command if isinstance(command, str) else command[0]
+        return 127, '', f"Command not found: {cmd_str}"
 
 
 def run_and_read_all(run_lambda, command):
@@ -148,7 +153,7 @@ def get_conda_packages(run_lambda, patterns=None):
     if patterns is None:
         patterns = DEFAULT_CONDA_PATTERNS
     conda = os.environ.get('CONDA_EXE', 'conda')
-    out = run_and_read_all(run_lambda, "{} list".format(conda))
+    out = run_and_read_all(run_lambda, [conda, 'list'])
     if out is None:
         return out