linux 系統管理與安全：基本 linux 系統知識
TRANSCRIPT
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•$ man [section] <program>
LS(1) User Commands LS(1)
NAMEls -‐ list directory contents
SYNOPSISls [OPTION]... [FILE]...
DESCRIPTIONList information about the FILEs (the current directory by default). Sort entries alphabeti-‐cally if none of -‐cftuvSUX nor -‐-‐sort is specified.
Mandatory arguments to long options are mandatory for short options too.
-‐a, -‐-‐alldo not ignore entries starting with .
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• $ echo -‐e "abc\na"abca
• STDIN (0)
• STDOUT (1)
• STDERR (2)
• $ cat /etc/passwd > users.txt(STDOUT)-‐
• $ cat /etc/passwd >> users.txt(STDOUT)-‐
• $ mail -‐s "Test mail" < letter.txt(STDIN)
• $ cat /etc/passwd 2> errors.txt( STDERR)
• $ find /etc > /dev/null( STDOUT)
• $ sh script.sh > /dev/null 2>&1( )
• $ sh script.sh | tee -‐a log.txt | other_program( log.txt other_program)
• $ sh script.sh | xargs other_program( other_program )
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• $ cat /etc/passwd | program
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• users.txt snowman $ grep snowman users.txt
• txt snowman $ grep snowman *.txt
• $ ifconfig | grep 'eth0' -‐-‐color=auto
•$ grep -‐r 'some_text' /etc/
•$ grep –e '^Snowman$' users.txt
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• $ find [ ] [ ]
• -‐name
• -‐perm
• -‐type
• -‐mtime
• $ find /etc -‐name passwd
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• $ sed [ ] < >
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• passwd 2~5 $ nl /etc/passwd | sed '2,5d'
• passwd 5~7 $ nl /etc/passwd | sed -‐n '5,7p'
•$ sed 's/ / /g'
• $ ifconfig enp0s3 | grep 'inet' \| sed 's/^.*inet //g' | sed 's/netmask.*$//g'
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• awk ' '
• awk '{ }' {}
• awk ' { }' {}
• sed awk
• tab $ last -‐n 5 | awk '{print $1 "\t" $3}'
• $ free -‐htotal used free shared buffers cached
Mem: 7.8G 7.6G 168M 18M 440M 3.0G-‐/+ buffers/cache: 4.1G 3.6G
2.0G 232K 2.0G
• $ free -‐h | awk '/Mem/{print $3}'7.6G
• STDIN
• /tmp core $ find /tmp -‐name '*core*' -‐type f -‐print | xargs/bin/rm -‐f
• /etc 664 $ find /etc -‐perm -‐664 | xargs ls –l
• cat
• head
• tail
• sort
• more/less
• nl
• cut
• uniq
• wc
• $ cat /proc/loadavg0.48 0.47 0.55 2/347 9893
• $ cat /proc/loadavg | [...]0.48
• $ cat /proc/meminfoMemTotal: 8138396 kBMemFree: 2895168 kBBuffers: 599540 kB...
• $ cat /proc/meminfo | [...]2895168
1. $ cat /proc/loadavg | awk '{print $1}'
2. $ cat /proc/meminfo | grep MemFree | awk '{print $2}'
• ls
• cd <path>
• pwd
• file <file>
• mkdir <folder>
• rmdir <folder>
• touch <filename>
• ln <destination> <source>
$ ls -‐al-‐rwxr-‐xr-‐-‐ 1 sntc06 sntc06 2.6K Oct 8 2012 action.php
-‐rwxr-‐xr-‐-‐
-‐: regular filed: directoryl: symbolic linkc: character deviceb: block devices: socketp: named pipe
$ ls -‐al-‐rwxr-‐xr-‐-‐ 1 sntc06 sntc06 2.6K Oct 8 2012 action.php
-‐rwxr-‐xr-‐-‐
Owner permissionr: readw: writex: execute
Group:r-‐xOthers:r-‐-‐
$ ls -‐al-‐rwxr-‐xr-‐-‐ 1 sntc06 sntc06 2.6K Oct 8 2012 action.php
-‐rwxr-‐xr-‐-‐
Owner permissionr: 100: 4w: 010: 2x: 001: 1
-‐> 754
Example:
$ chmod 644 action.php$ chmod a+x action.php$ chmod -‐w action.php
$ ls -‐al-‐rwxr-‐xr-‐-‐ 1 sntc06 sntc06 2.6K Oct 8 2012 action.php
$ ls -‐al-‐rwxr-‐xr-‐-‐ 1 sntc06 sntc06 2.6K Oct 8 2012 action.php
$ ls -‐al-‐rwxr-‐xr-‐-‐ 1 sntc06 sntc06 2.6K Oct 8 2012 action.php
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• # mount /dev/sdd1 /media/usb-‐drive
• # mount -‐o remount,ro -‐t ext4 /dev/sda1 /home-‐o [ ] -‐t [ ]
•# umount /media/usb-‐drive
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• init / systemd
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• process$ ps -‐l
• process# ps axu
• process tree# ps axjf
1 2827 2827 2827 ? -‐1 Ss 1003 0:00 SCREEN2827 2828 2828 2828 pts/4 2836 Ss 1003 0:00 \_ /bin/zsh2828 2836 2836 2828 pts/4 2836 S+ 1003 0:00 | \_ /bin/bash ./start.sh2836 2837 2836 2828 pts/4 2836 Sl+ 1003 207:14 | \_ java -‐server …2827 3025 3025 3025 pts/8 3025 Ss+ 1003 0:00 \_ /bin/zsh
root 27850 0.0 0.0 113908 4332 ? Ss Apr01 0:00 sshd: sntc06 [priv]sntc06 27976 0.0 0.0 114048 2080 ? S Apr01 0:00 sshd: sntc06@pts/6sntc06 27977 0.0 0.0 52076 6388 pts/6 Ss+ Apr01 0:00 -‐zsh
F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD0 S 1000 8755 8754 0 80 0 -‐ 12210 sigsus pts/11 00:00:00 zsh0 R 1000 9082 8755 0 80 0 -‐ 3383 -‐ pts/11 00:00:00 ps
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• Ctrl+Z
• fg
• bg
• jobs
• shell & $ ping localhost &
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No.
1 SIGHUP log file2 SIGINT Interrupt (Ctrl+C)
3 SIGQUIT
9 SIGKILL
15 SIGTERM
18 SIGCONT
19 SIGSTP (Ctrl+Z)
$ man 7 signal
• pid
• kill [-‐signal] <pid>
• PID 5566 # kill 5566# kill -‐15 5566
• PID 5566 # kill -‐9 5566
• PGID 5566 # kill -‐1 -‐5566( )
• PID
• root PID$ pgrep -‐u root -‐l
• httpd$ pgrep httpd -‐l
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• pkill [-‐signal] < >
• httpd# pkill httpd
• httpd# pkill -‐9 httpd
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• /etc/rcX.d/
• /etc/init.d/
• sysvinit upstartinit
•$ systemctl
• / /# systemctl start/stop/restart <service>
• /# systemctl status/is-‐enabled <service>
• /# systemctl enable/disable <service>
root:~/ # systemctl status httpdhttpd.service -‐ The Apache HTTP Server
Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)Active: active (running) since 2015-‐04-‐01 16:10:40 CST; 10min ago
Main PID: 1221 (httpd)Status: "Total requests: 0; Current requests/sec: 0; Current traffic: 0 B/sec"CGroup: /system.slice/httpd.service
├─1221 /usr/sbin/httpd -‐DFOREGROUND├─2475 /usr/sbin/httpd -‐DFOREGROUND├─2476 /usr/sbin/httpd -‐DFOREGROUND├─2477 /usr/sbin/httpd -‐DFOREGROUND├─2478 /usr/sbin/httpd -‐DFOREGROUND└─2479 /usr/sbin/httpd -‐DFOREGROUND
4 01 16:10:37 localhost.localdomain httpd[1221]: AH00558: httpd: ...4 01 16:10:40 localhost.localdomain systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -‐l to show in full.
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[Unit]Description=The Apache HTTP ServerAfter=network.target remote-‐fs.target nss-‐lookup.target
[Service]Type=notifyEnvironmentFile=/etc/sysconfig/httpdExecStart=/usr/sbin/httpd $OPTIONS -‐DFOREGROUNDExecReload=/usr/sbin/httpd $OPTIONS -‐k gracefulExecStop=/bin/kill -‐WINCH ${MAINPID}# We want systemd to give httpd some time to finish gracefully, but still want# it to kill httpd after TimeoutStopSec if something went wrong during the# graceful stop. Normally, Systemd sends SIGTERM signal right after the# ExecStop, which would kill httpd. We are sending useless SIGCONT here to give# httpd time to finish.KillSignal=SIGCONTPrivateTmp=true
[Install]WantedBy=multi-‐user.target
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• at
• crontab
•$ crontab -‐l
•$ crontab -‐e
• root # crontab -‐u root
root:/dev/ # at 18:30 2015-‐04-‐01at> echo "Happy April Fools!" > /dev/pts/0at> <EOT>job 2 at Wed Apr 1 18:20:00 2015
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• /etc/crontab, /etc/cron.d/SHELL=/bin/bashPATH=/sbin:/bin:/usr/sbin:/usr/binMAILTO=root
#m h dom mon dow user command0 0 * * 1 root /bukkit_backup/backup.sh >> /dev/null 2>&1*/30 8-‐17 * * 1-‐5 root /root/check_website.sh
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• /etc/cron.daily/
• /etc/cron.weekly/
• /etc/cron.monthly/
#period in days delay in minutes job-‐identifier command1 5 cron.daily nice run-‐parts /etc/cron.daily7 25 cron.weekly nice run-‐parts /etc/cron.weekly@monthly 45 cron.monthly nice run-‐parts /etc/cron.monthly
• mariadb
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• *.rpm
•# rpm -‐i package.rpm
•# rpm -‐U package.rpm
•# rpm -‐i package.rpm -‐-‐test -‐v
•# rpm -‐e package
•# rpm -‐q -‐a
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•# yum check-‐update
•# yum update mosh
•# yum install mosh
•# yum remove mosh
•# yum list installed
•# yum search mosh
•# yum info mosh
• mariadb
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• /etc/passwd
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• /etc/group
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root:x:0:0:root:/root:/bin/zsh
root:x:0:user1,user2
• /etc/shadow
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•$ passwd
•# passwd sntc06
•# useradd [ ] < >
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• -‐m
• -‐c
• -‐u UID
• -‐g GID
• -‐G
• -‐s login shell
• admin# groupadd admin
• test# groupdel test
• snowman admin# usermod -‐a -‐G admin snowman
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•$ su -‐ root ( login shell)$ su ( shell)
• snowman $ su snowman
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• snowman $ sudo -‐u snowman vim test.txt
• root $ sudo reboot
• root shell$ sudo su -‐
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## Allow root to run any commands anywhereroot ALL=(ALL) ALL
## Allows people in group wheel to run all commands%wheel ALL=(ALL) ALL
1.
2. sudo
3. su
4. sudo mariadb