diff --git a/puppet/zulip/files/postgresql/pg_backup_and_purge b/puppet/zulip/files/postgresql/pg_backup_and_purge
index d0f6d6d08d..9ee21a7fa9 100755
--- a/puppet/zulip/files/postgresql/pg_backup_and_purge
+++ b/puppet/zulip/files/postgresql/pg_backup_and_purge
@@ -2,6 +2,7 @@
 
 import sys
 import glob
+import shlex
 import subprocess
 import sys
 import logging
@@ -17,7 +18,7 @@ logger = logging.getLogger(__name__)
 def run(args, dry_run=False):
     # type: (List[str], bool) -> str
     if dry_run:
-        print("Would have run: " + " ".join(args))
+        print("Would have run: " + " ".join(map(shlex.quote, args)))
         return ""
 
     p = subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
diff --git a/scripts/lib/zulip_tools.py b/scripts/lib/zulip_tools.py
index fd0c594d6e..2f979c022a 100755
--- a/scripts/lib/zulip_tools.py
+++ b/scripts/lib/zulip_tools.py
@@ -7,6 +7,7 @@ import logging
 import os
 import pwd
 import re
+import shlex
 import shutil
 import subprocess
 import sys
@@ -153,7 +154,7 @@ def release_deployment_lock():
 def run(args, **kwargs):
     # type: (Sequence[str], **Any) -> None
     # Output what we're doing in the `set -x` style
-    print("+ %s" % (" ".join(args)))
+    print("+ %s" % (" ".join(map(shlex.quote, args)),))
 
     if kwargs.get('shell'):
         # With shell=True we can only pass string to Popen
@@ -163,7 +164,8 @@ def run(args, **kwargs):
         subprocess.check_call(args, **kwargs)
     except subprocess.CalledProcessError:
         print()
-        print(WHITEONRED + "Error running a subcommand of %s: %s" % (sys.argv[0], " ".join(args)) +
+        print(WHITEONRED + "Error running a subcommand of %s: %s" %
+              (sys.argv[0], " ".join(map(shlex.quote, args))) +
               ENDC)
         print(WHITEONRED + "Actual error output for the subcommand is just above this." +
               ENDC)
diff --git a/tools/diagnose b/tools/diagnose
index e7443b6fd0..8afcdc0ae0 100755
--- a/tools/diagnose
+++ b/tools/diagnose
@@ -2,6 +2,7 @@
 
 import os
 import platform
+import shlex
 import sys
 import subprocess
 
@@ -26,7 +27,7 @@ def run(check_func):
 
 def run_command(args):
     # type: (List[str]) -> None
-    print(' '.join(args))
+    print(' '.join(map(shlex.quote, args)))
     subprocess.check_call(args)
 
 @run