Harden the four monitoring scripts

set -euo pipefail across all four, but added deliberately rather than
pasted in -- each script needed the places where a non-zero exit is
normal handled first, or strict mode would have made them worse:

- sys_monitor / process_monitor: `ps | head -n 6` is a latent SIGPIPE.
  head closes the pipe after six lines, and on a host with enough
  processes ps fills the buffer and exits 141, which pipefail turns into
  a script abort -- on exactly the busy machine you wanted to inspect.
  Confirmed the mechanism (a large producer into head returns 141) and
  those pipelines now tolerate it.
- security_audit: find exits non-zero when it cannot read a directory,
  which is routine when walking the whole filesystem. Without handling,
  set -e aborted the audit part way while still looking complete. Also
  notes that a clean report as non-root means little, since find cannot
  descend where it may not read.
- network_info: iptables needs root, so the last section aborted the
  script for ordinary users. Now reports the failure, and falls back to
  nft where iptables is absent.

process_monitor also no longer kills on sight. `pkill -x` by name can
match several processes at once, and as root that is an easy way to take
down more than intended. It now prints what it matched and asks, with
FORCE=1 for unattended use and a refusal rather than a hang when there
is no tty.

All four run clean; the kill path was tested against a live process and
left it alive.

network_info.sh

@@ -17,6 +17,11 @@
 # 
 # Usage: network_info.sh    (no arguments)
 # Description: Displays network interface addresses, routing table, open ports, and iptables rules.
+#
+# Read-only. The iptables section needs root; without it that section
+# reports the failure rather than silently showing nothing.
+
+set -euo pipefail
 
 echo "==== Network Interfaces (IP addresses) ===="
 if command -v ip &> /dev/null; then
@@ -47,7 +52,10 @@ fi
 
 echo -e "\n==== Firewall Rules (iptables) ===="
 if command -v iptables &> /dev/null; then
-  iptables -L -n -v    # list firewall rules with numeric addresses and packet counts
+  # Needs root; report the failure instead of letting set -e abort here.
+  iptables -L -n -v || echo "Could not read iptables rules (run as root?)."
+elif command -v nft &> /dev/null; then
+  nft list ruleset || echo "Could not read nftables ruleset (run as root?)."
 else
   echo "iptables command not found (no firewall rules to show or using nftables)."
 fi

process_monitor.sh

@@ -18,23 +18,47 @@
 # Usage: process_monitor.sh [kill <process_name|PID>]
 # Description: Without args, shows top CPU & memory processes. With "kill", terminates process by name or PID.
 
-if [ "$1" = "kill" ]; then
+set -euo pipefail
+
+if [ "${1:-}" = "kill" ]; then
   target="$2"
   if [ -z "$target" ]; then
     echo "Usage: $0 kill <process_name|PID>"; exit 1
   fi
-  # If target is numeric (PID), kill that PID, else kill by name
+  # Show what will be signalled and confirm first. pkill -x by name can
+  # match several processes at once, and as root that is an easy way to
+  # take down more than intended with no warning.
   if [[ "$target" =~ ^[0-9]+$ ]]; then
-    kill "$target" && echo "Process $target killed." || echo "Failed to kill process $target."
+    if ! ps -p "$target" -o pid,user,comm >/dev/null 2>&1; then
+      echo "No process with PID $target."; exit 1
+    fi
+    ps -p "$target" -o pid,user,comm
   else
-    # Use pkill to kill by name (match full process name)
-    pkill -x "$target" && echo "Processes named '$target' killed." || echo "No process '$target' found or kill failed."
+    if ! pgrep -x "$target" >/dev/null 2>&1; then
+      echo "No process named '$target'."; exit 1
+    fi
+    pgrep -x -a "$target"
+  fi
+
+  if [ "${FORCE:-}" != "1" ]; then
+    if [ ! -t 0 ]; then
+      echo "Refusing to kill without confirmation; set FORCE=1 for unattended use." >&2
+      exit 1
+    fi
+    read -r -p "Send SIGTERM to the above? (yes/NO): " reply
+    [ "$reply" = "yes" ] || { echo "Cancelled."; exit 0; }
+  fi
+
+  if [[ "$target" =~ ^[0-9]+$ ]]; then
+    kill "$target" && echo "Process $target signalled." || echo "Failed to signal process $target."
+  else
+    pkill -x "$target" && echo "Processes named '$target' signalled." || echo "Failed to signal '$target'."
   fi
   exit 0
 fi
 
 echo "==== Top 5 CPU-consuming processes ===="
-ps -eo pid,user,comm,%cpu --sort=-%cpu | head -n 6
+ps -eo pid,user,comm,%cpu --sort=-%cpu | head -n 6 || true
 
 echo -e "\n==== Top 5 Memory-consuming processes ===="
-ps -eo pid,user,comm,%mem --sort=-%mem | head -n 6
+ps -eo pid,user,comm,%mem --sort=-%mem | head -n 6 || true

security_audit.sh

@@ -17,18 +17,29 @@
 # 
 # Usage: security_audit.sh   (no arguments)
 # Description: Lists world-writable files/dirs, SUID/SGID files, and listening ports.
+#
+# Run as root for a complete picture: as an unprivileged user, find
+# cannot descend into directories it may not read, so a clean report
+# below is not the same as a clean system.
+
+set -euo pipefail
+
+# Each find below ends in `|| true`. find exits non-zero when it could
+# not read some directory -- routine here, since we deliberately walk the
+# whole filesystem -- and without this, set -e would abort the audit part
+# way through and still look like it had finished.
 
 # World-writable files (perm bits: others have write)
 echo "==== World-Writable Files (potentially unsafe) ===="
-find / -xdev -type f -perm -0002 -printf '%M %u %g %p\n' 2>/dev/null
+find / -xdev -type f -perm -0002 -printf '%M %u %g %p\n' 2>/dev/null || true
 
 # World-writable directories without sticky bit
 echo -e "\n==== World-Writable Directories (no sticky bit) ===="
-find / -xdev -type d -perm -0002 ! -perm -1000 -printf '%M %u %g %p\n' 2>/dev/null
+find / -xdev -type d -perm -0002 ! -perm -1000 -printf '%M %u %g %p\n' 2>/dev/null || true
 
 # SUID/SGID files (files with setuid or setgid bits)
 echo -e "\n==== SUID/SGID Files ===="
-find / -xdev \( -perm -4000 -o -perm -2000 \) -printf '%M %u %g %p\n' 2>/dev/null
+find / -xdev \( -perm -4000 -o -perm -2000 \) -printf '%M %u %g %p\n' 2>/dev/null || true
 
 # Open listening ports
 echo -e "\n==== Listening Network Ports ===="

sys_monitor.sh

@@ -18,6 +18,14 @@
 # Usage: sys_monitor.sh    (no arguments)
 # Description: Prints system uptime, memory, disk usage, and top CPU/mem processes.
 
+set -euo pipefail
+
+# `ps | head` is a SIGPIPE waiting to happen: head closes the pipe after
+# six lines, and on a host with enough processes ps fills the buffer and
+# dies with 141, which pipefail turns into a script exit. That is exactly
+# the busy machine you most want this to work on, so those two pipelines
+# tolerate it explicitly.
+
 echo "==== System Uptime and Load ===="
 uptime
 
@@ -30,7 +38,7 @@ df -h -x tmpfs -x devtmpfs
 
 echo -e "\n==== Top 5 Processes by CPU Usage ===="
 # Display header and top 5 CPU-consuming processes
-ps -eo pid,user,comm,%cpu --sort=-%cpu | head -n 6
+ps -eo pid,user,comm,%cpu --sort=-%cpu | head -n 6 || true
 
 echo -e "\n==== Top 5 Processes by Memory Usage ===="
-ps -eo pid,user,comm,%mem --sort=-%mem | head -n 6
+ps -eo pid,user,comm,%mem --sort=-%mem | head -n 6 || true