Comprehensive Guide to System Monitoring, Text Editing, Permission Management, and Log Analysis for Library Operations

System Monitoring – top Deep Optimization

1.1 Performance Bottleneck Detection Techniques

Scenario: Investigating system lag during peak borrowing periods.

# Capture top‑5 resource‑consuming processes in real time
 top -bn1 | grep "library_app" | awk '{print "CPU usage:"$9"% Memory usage:"$10"% PID:"$1}'

Memory Leak Investigation

# Sample memory data for 60 seconds
for i in {1..60}; do
    top -bn1 -p 4563 > /tmp/mem.log   # 4563 is the suspected PID
    sleep 1
done
# Generate memory usage curve
awk '/4563/ {print $10}' /tmp/mem.log > mem_usage.csv

1.2 Automated Monitoring Script

#!/bin/bash
# Resource threshold alarm script
CPU_THRESHOLD=90
MEM_THRESHOLD=85
while true; do
    CPU_USAGE=$(top -bn1 | grep "Cpu(s)" | awk '{print $2}')
    MEM_USAGE=$(free | awk '/Mem/ {print $3/$2 * 100.0}')
    if (( $(echo "$CPU_USAGE > $CPU_THRESHOLD" | bc -l) )); then
        echo "[URGENT] CPU usage exceeded threshold! Current: ${CPU_USAGE}%" | mail -s "System Alert" [email protected]
    fi
    if (( $(echo "$MEM_USAGE > $MEM_THRESHOLD" | bc -l) )); then
        echo "[URGENT] Memory usage exceeded threshold! Current: ${MEM_USAGE}%" | mail -s "System Alert" [email protected]
    fi
    sleep 300
done

Text Editing – vim Efficient Operations Manual

2.1 Bulk Book Information Modification Example

Original data:

《Linux入门》| 王伟 | 2020 | 库存:5
《数据库原理》| 李芳 | 2018 | 库存:2

Task requirements:

Add Chinese book‑title brackets around all titles.

Mark books published before 2018 with [Pending Update] .

Add red‑color warning for stock lower than 3.

Operation steps (Vim commands):

Column selection: Ctrl+v → select column → I《 → Esc

Range replacement: :%s/| \d{4} |/& [Pending Update]/g

Conditional highlight: add to ~/.vimrc the rule match ErrorMsg /库存:[0-2]/

Permission Management – chmod Security Guidelines

3.1 Library Permission Matrix 2.0

Role

Directory Permission

File Permission

Control Method

Library Administrator

755 (rwxr-xr-x)

644 (rw-r--r--)

ACL restriction:

setfacl -m g:editor:rwx /upload

Auditor

550 (r-xr-x---)

440 (r--r-----)

Enable sudo logging:

Defaults logfile=/var/log/sudo.log

External Collaborator

750 (rwxr-x---)

640 (rw-r-----)

Immutable attribute:

chattr +i important_file.txt

3.2 Permission Inheritance Anomaly Handling

Fault: Newly uploaded files acquire 777 permissions, causing data leakage.

Investigation steps:

# 1. Check umask (should be 0027)
umask
# 2. Inspect directory special bits
ls -ld /upload   # SGID bit found
# 3. Reset security configuration
chmod 2770 /upload
find /upload -type f -exec chmod 660 {} \;

Log Processing – grep Advanced Query Techniques

4.1 Multi‑Condition Log Analysis

Retrieve abnormal borrowing records from the last hour:

grep -E "失败|异常" /logs/borrow.log |
awk -v d1="$(date -d '1 hour ago' +'%Y-%m-%d %H:%M')" -v d2="$(date +'%Y-%m-%d %H:%M')" '$0 > d1 && $0 < d2'

4.2 Performance Benchmark Comparison

Test with a 1‑million‑line log file:

# Generate test data
dd if=/dev/urandom of=test.log bs=1M count=1000
# Compare tools
hyperfine "grep 'ERROR' test.log" "ack 'ERROR' test.log" "rg 'ERROR' test.log"

Results:

Tool

Average Time

Memory Usage

grep

1.28s

12MB

ack

0.98s

18MB

ripgrep

0.41s

8MB

Comprehensive Application – Borrowing Behavior Analysis Pipeline

Generate daily top‑10 hot books:

# Extract book titles
cat borrow.log | grep -oP "借阅《\K[^》]+" | sort | uniq -c | sort -nr | head -10 > daily_top10.txt
# Visualize (requires termgraph)
cat daily_top10.txt | termgraph --title "Hot Books Ranking"

Sample output:

▇▇▇▇▇▇▇▇▇▇ 125 《Linux系统管理》
▇▇▇▇▇▇▇▇▇ 112 《Python数据分析》
▇▇▇▇▇▇▇▇ 98 《数据库优化指南》

Quick Troubleshooting Cheat Sheet

6.1 High‑Frequency Issue Quick‑Check Table

Fault Symptom

First Diagnostic Command

Follow‑up Steps

New book entry system hangs

vmstat 1

(check I/O wait)

df -h

(disk space) and investigate slow SQL

Reader cannot log in

tail -f /var/log/auth.log

Check PAM config

/etc/pam.d/login

Search results abnormal

strace -p

Check index file permissions

ls -l /index

Database connections surge

ss -tn src :3306

Inspect connection pool

max_connections

Operational Safety Golden Rules

Before high‑risk actions, always: cp critical_file{,.bak} # backup screen -S operation # protect session echo "$(date) operation start" >> /var/log/ops.log # timestamp

When modifying important config files: vim /etc/nginx.conf && nginx -t && systemctl reload nginx

Validate batch commands before execution: echo "rm -rf /tmp/old_logs/" # preview !! # execute after confirmation

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