Linux Command Cheatsheet and Java Diagnostic Tools for System Operations

Preface

In daily work we often encounter difficult problems; this note records useful Linux commands and Java diagnostic tools as a personal reference and to share with colleagues.

Linux command collection

tail

Commonly used tail -300f shopbase.log to display the last 300 lines and follow the file.

grep

Examples of searching files and directories, including multi‑file search, recursive search, case‑insensitive, include/exclude patterns, and context options.

grep forest f.txt      # file search
grep forest f.txt cpf.txt   # multi‑file search
grep 'log' /home/admin -r -n   # recursive search
cat f.txt | grep -i shopbase
grep 'shopbase' /home/admin -r -n --include *.{vm,java}   # include extensions
grep 'shopbase' /home/admin -r -n --exclude *.{vm,java}   # exclude
seq 10 | grep 5 -A 3   # after match
seq 10 | grep 5 -B 3   # before match
seq 10 | grep 5 -C 3   # context
cat f.txt | grep -c 'SHOPBASE'

awk

Basic usage, pattern matching and built‑in variables (NR, FNR, NF) with examples.

awk '{print $4,$6}' f.txt
awk '{print NR,$0}' f.txt cpf.txt
awk '{print FNR,$0}' f.txt cpf.txt
awk '{print FNR,FILENAME,$0}' f.txt cpf.txt
awk '{print FILENAME,"NR="NR,"FNR="FNR,"$"NF"="$NF}' f.txt cpf.txt
echo 1:2:3:4 | awk -F: '{print $1,$2,$3,$4}'
# matching examples
awk '/ldb/ {print}' f.txt
awk '!/ldb/ {print}' f.txt
awk '/ldb/ && /LISTEN/ {print}' f.txt
awk '$5 ~ /ldb/ {print}' f.txt

find

Various find command usages for searching files by name, type, size, permissions, and time.

sudo -u admin find /home/admin /tmp /usr -name *.log
find . -iname *.txt
find . -type d
find /usr -type l
find /usr -type l -name "z*" -ls
find /home/admin -size +250000k
find /home/admin -perm 777 -exec ls -l {} ;
find /home/admin -atime -1
find /home/admin -ctime -1
find /home/admin -mtime -1
find /home/admin -amin -1
find /home/admin -cmin -1
find /home/admin -mmin -1

pgm

Batch query logs for vm‑shopbase.

pgm -A -f vm-shopbase 'cat /home/admin/shopbase/logs/shopbase.log.2017-01-17|grep 2069861630'

tsar

Company‑internal metric collection tool; examples to view recent day, live metrics, specific date, and individual metrics.

tsar   # recent day metrics
tsar --live   # live metrics, refresh every 5 seconds
tsar -d 20161218   # specific day (up to four months)
tsar --mem
tsar --load
tsar --cpu

top / ps

Use ps -ef | grep java and top -H -p pid to locate Java threads, then convert thread IDs for jstack analysis.

Other diagnostic tools

Includes btrace, Greys, javOSize, JProfiler, Eclipse MAT, zprofiler, jps, jstack, jinfo, jmap, jstat, jdb, CHLSDB, and various IntelliJ plugins. Typical commands are shown below.

# btrace example (monitor ArrayList.add when size>500)
# Greys sc -df xxx (class detail)
# jps -mlvV
sudo -u admin /opt/taobao/java/bin/jstack 2815
sudo -u admin /opt/taobao/java/bin/jstack -m 2815
sudo -u admin /opt/taobao/java/bin/jinfo -flags 2815
sudo -u admin /opt/taobao/java/bin/jmap -heap 2815
sudo -u admin /opt/taobao/java/bin/jmap -dump:live,format=b,file=/tmp/heap2.bin 2815
sudo -u admin /opt/taobao/java/bin/jmap -histo 2815 | head -10
sudo -u admin /opt/taobao/java/bin/jstat -gcutil 2815 1000
sudo -u admin /opt/taobao/java/bin/jdb -attach 8000