Linux Log Assistant

Linux Log Search and Archive Extraction Command Quick Reference

Log Search Commands

Common Linux log search and filtering commands, including tools like grep, awk, sed

Basic Search

grep "keyword" /var/log/syslog

Search for lines containing the keyword in log files

grep -i "error" /var/log/syslog

Search for 'error' ignoring case

grep -c "error" /var/log/syslog

Count matching lines

grep -n "error" /var/log/syslog

Display line numbers of matching lines

grep -C 3 "error" /var/log/syslog

Display matching lines and 3 lines of context before and after

grep -B 5 "error" /var/log/syslog

Display matching lines and 5 lines before

grep -A 5 "error" /var/log/syslog

Display matching lines and 5 lines after

grep -v "debug" /var/log/syslog

Exclude lines containing 'debug'

grep -r "error" /var/log/

Recursively search all files in the directory

grep -l "error" /var/log/*

Only display filenames containing matching content

grep -F "error" /var/log/*.log

Search for lines containing the fixed string 'error' in log files (does not support regular expressions)

Time Filtering

journalctl --since "2024-01-01 00:00:00"

View logs after a specified time

journalctl --until "2024-01-01 23:59:59"

View logs before a specified time

journalctl --since today

View today's logs

journalctl --since yesterday --until today

View yesterday's logs

journalctl --since "1 hour ago"

View logs from the last 1 hour

journalctl --since "30 minutes ago"

View logs from the last 30 minutes

sed -n '/Jan 01 10:00/,/Jan 01 12:00/p' /var/log/syslog

Extract logs within a specified time range

awk '/2024-01-01 10:/ && /2024-01-01 12:/' /var/log/app.log

Filter time range using awk

Pattern Matching

grep -E "error|warning|critical" /var/log/syslog

Match multiple keywords using regular expressions

grep -w "error" /var/log/syslog

Exactly match whole words

grep -E "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}" /var/log/auth.log

Match IP addresses

grep -E "[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}" /var/log/mail.log

Match email addresses

awk '{print $1, $2, $3}' /var/log/syslog

Extract the first three fields of logs

awk '$9 >= 500' /var/log/nginx/access.log

Filter requests with HTTP status code >= 500

sed 's/password=[^ ]*/password=****/g' /var/log/app.log

Replace sensitive information in logs

cut -d' ' -f1,2,3 /var/log/syslog

Split by space and extract specified fields

Real-time Monitoring

tail -f /var/log/syslog

Real-time log file tracking

tail -n 100 /var/log/syslog

View the last 100 lines of logs

tail -f /var/log/syslog | grep --line-buffered "error"

Real-time tracking and keyword filtering

tail -f /var/log/syslog /var/log/auth.log

Track multiple log files simultaneously

journalctl -f

Real-time tracking of systemd logs

journalctl -u nginx.service -f

Real-time tracking of logs for a specified service

less +F /var/log/syslog

Real-time tracking using less (press Ctrl+C to stop, F to continue)

multitail /var/log/syslog /var/log/auth.log

View multiple logs simultaneously in split screen (multitail installation required)

Combined Commands

cat /var/log/syslog | grep "error" | grep -v "debug"

Combine multiple filter conditions

grep "error" /var/log/syslog | sort | uniq -c | sort -rn

Count error occurrences and sort

awk '{sum+=$10} END {print sum}' /var/log/nginx/access.log

Zliczanie sumy pól (np. rozmiaru odpowiedzi)

find /var/log -name "*.log" -exec grep -l "error" {} \;

Szukanie w wielu plikach dziennika

zgrep "error" /var/log/syslog.*.gz

Szukanie w skompresowanych plikach dziennika

zcat /var/log/syslog.1.gz | grep "error"

Rozpakowywanie i szukanie w skompresowanych dziennikach

find /var/log -name "*.log" | xargs grep "error"

Szukanie wsadowe przy użyciu xargs

grep "error" /var/log/syslog | tee errors.txt

Wyniki szukania są wyświetlane na ekranie i zapisywane do pliku

Common Log Files

/var/log/syslog

Dziennik systemowy (Debian/Ubuntu)

/var/log/messages

Dziennik systemowy (RHEL/CentOS)

/var/log/auth.log

Dziennik uwierzytelniania (logowanie, sudo itp.)

/var/log/secure

Dziennik bezpieczeństwa (RHEL/CentOS)

/var/log/dmesg

Dziennik uruchamiania jądra

/var/log/kern.log

Dziennik jądra

/var/log/nginx/access.log

Dziennik dostępu Nginx

/var/log/nginx/error.log

Dziennik błędów Nginx

/var/log/apache2/access.log

Dziennik dostępu Apache

/var/log/apache2/error.log

Dziennik błędów Apache

/var/log/mysql/error.log

Dziennik błędów MySQL

docker logs <container_name>

Dzienniki kontenera Docker

📖Introdução à ferramenta.

The Linux Log Assistant is a command quick reference tool designed for system administrators and developers, covering common commands for log searching, filtering, and compressed file decompression. Whether troubleshooting system failures, analyzing application logs, or processing log files in various compressed formats, you can quickly find the necessary commands here. All commands are accompanied by clear explanations and support one-click copying, helping you perform log analysis and operations more efficiently.

Recursos.

6 major log search categories, covering scenarios such as basic search, time filtering, and pattern matching

Support for 7 compression formats, including tar, gzip, zip, bzip2, xz, rar, 7z

Each format includes single-file and batch decompression commands

70+ common commands, comprehensively collected from basic to advanced

Supports keyword search to quickly locate desired commands

One-click command copying to improve work efficiency

Clear explanations, easy to understand and learn

Category browsing and filtering to quickly find relevant commands

❓Perguntas frequentes.

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Linux Log Assistant

📖Introdução à ferramenta.

Recursos.

❓Perguntas frequentes.

Why do you need Linux Log Assistant?

Which log search scenarios are supported?

Which compression formats are supported for decompression?

How to quickly find the commands you need?

Can the copied commands be used directly?

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