Ubuntu Linux learning comes with notes record.
basic command
pwd 打印当前工作路径
ls 显示当前路径下的内容
mkdir 创建文件夹
touch 创建文件
cp 文件名 文件名 复制
rm 删除文件
rmdir 删除文件夹
rm -r filename # 删除文件夹（该文件夹下有内容时-r）
clear # 清空当前屏幕
man command or command --help # 帮助命令
wc filename # 打印出文件的行数-l，字数-w，字符数-m，最长一行的字符数-L
last # 列出最近的用户登录日志
lsblk # 列出所有block device -a
User, Group, Permission
add user
useradd -d /home/username -m -s /bin/bash username
# -d specify home dir
# -s create home dir if not exist
# -s specify bash path
# -g specify primary group (it is default)
# -G specify secondary group, could use comma sperate when specify multipal secondary group meantime
userdel -r username # -r remove home dir
set new user password
passwd username
Group
MaxNumber of group 65536
usermod -a -G groupname username
# -a append group rather than overwrite, or use comma like above
some command
id
groups [username]
members -a groupname
chown # change owner
chown username:groupname target
chown username target
chown :groupname target # becareful colone symbal
chown -R username filename
chown -R username:groupname target # -R recursive
chmod # change permissions for file or directory
chmod permission-set target
chmod 666 filename
chmod -R 777 directoryname
chmod --reference=b.txt a.txt # 将b.txt文件的权限属性作为模板，更改a.txt文件
chmod -c u+x b.txt # -c 显示更改详情
chmod g+w painting-of-Mordor.png # Add group write permission to file
chmod u=x script.sh # Only allow user execution permissionto file
chmod a-w do-not-edit.txt # Remove all (ugo) write permissionto file
u: owner: file's owner
g: group: users who are members of the file's group
o: other: users who are neither the file's owner nor members of the file's group
a: all: all three of the above, same as ugo
+: adds the specified modes to the specified classes
-: removes the specified modes from the specified classes
=: the modes specified are to be made the exact modes for the specified classes
r: read: read a file or list a directory's contents
w: write: write to a file or directory
x: execute: execute a file or recurse a directory tree
setfacl
setfacl -m g:groupname:rwx /dir # 给文件夹添加多个组
setfacl -m u:username:rwx /dir # 给文件夹添加多个用户
setfacl -x g:groupname /dir # cancel
setfacl -x u:username /dir # cancel
getfacl /dir # 查看，因为默认只显示一个组
解决笔记本装完无法发现无线网络的问题：
sudo apt install bcmwl-kernel-source
sudo apt-get install linux-headers-generic build-essential dkms
sudo apt-get update(optional maybe)
sudp apt-get install linux-source
sudo apt-get install --reinstall bcmwl-kernel-source #（有可能只需要执行该步骤即可成功）
sudo modprobe wl
sudo dpkg -i wireless-bcm43142-dkms_6.20.55.19-1_amd64.deb
图形界面下，开启登录到命令行
sudo systemctl set-default multi-user.target
sudo systemctl start lightdm
systemctl set-default graphical.target
# 默认进入图形界面
Sharing Write Permission
为了分享同一目录的多用户写入权限，把该目录的写入权限授予一个分组是必要的。
下面的例子把/var/www/html目录的写入权限授予”webmasters”分组。
sudo chgrp -R webmasters /var/www/html
sudo find /var/www/html -type d -exec chmod g=rwxs "{}" \;
sudo find /var/www/html -type f -exec chmod g=rw "{}" \;
这些命令递归地设置组权限到/var/www/html下的所有文件和目录，以保证该组用户对该目录的读写权限。
也就是说，该目录下的文件和目录将从它们的父亲继承相应的组权限。
如果必须授权一个目录的访问到多个组，允许访问控制列表(ACLs)。
Ubuntu下apache2无法解析php文件，浏览器提示下载所要打开的php文件. 执行：
sudo apt-get install libapache2-mod-php5
sudo a2enmod php5
如果显示为：
This module does not exist!
那就要彻底删除libapache2-mod-php5，然后重新安装它
sudo apt-get remove –purge libapache2-mod-php5
sudo apt-get install libapache2-mod-php5
重启apache2
sudo /etc/init.d/apache2 restart
open PDF file on bash
xdg-open xxx.pdf
gio open xxx.pdf
okular xxx.pdf
查找进程，计算器，替换大小写
ps -ef | grep processname
who | tr [a-z] [A-Z] > /tmp/file.out
tr 'a-z' 'A-Z' > /tmp/file.out
echo {1..100} | tr ' ' '+' | bc
find /var/www/html -maxdepth 1 -name ".*" // 不迭代子文件夹，只搜索一级目录
find /etc -maxdepth 1 -name "s*" | head -n 10 // tail -n 10
find /etc -maxdepth 1 -type d -name "s*"
grep t[ae]st hello.txt // 匹配括号中的任何一个，且只有一个
grep [^g]oo hello.txt // 匹配不是以g开头的任何字符
grep '^A' test.txt // 表示输出以A开头的
grep '$A' test.txt // 表示输出以A结尾的行
grep '^$' test.txt // 找空行
rep 'f..' test.txt // 表示输出 f后面跟2个字节的行
grep 'f*' test.txt // 匹配f后面不限制字符
x\{m\} #重复字符x，m次，如：'o\{5\}'匹配包含5个o的行。
x\{m,\} #重复字符x,至少m次，如：'o\{5,\}'匹配至少有5个o的行。
x\{m,n\} #重复字符x，至少m次，不多于n次，如：'o\{5,10\}'匹配5--10个o的行。
.* #一起用代表任意字符。
\(..\) #标记匹配字符，如'\(love\)'，love被标记为1。
\< #锚定单词的开始，如:'\<grep'匹配包含以grep开头的单词的行。
\> #锚定单词的结束，如'grep\>'匹配包含以grep结尾的单词的行。
\w #匹配文字和数字字符，也就是[A-Za-z0-9]，如：'G\w*p'匹配以G后跟零个或多个文字或数字字符，然后是p。
\W #\w的反置形式，匹配一个或多个非单词字符，如点号句号等。
\b #单词锁定符，如: '\bgrep\b'只匹配grep。
. (dot) - a single character.
? - the preceding character matches 0 or 1 times only.
* - the preceding character matches 0 or more times.
+ - the preceding character matches 1 or more times.
{n} - the preceding character matches exactly n times.
{n,m} - the preceding character matches at least n times and not more than m times.
[agd] - the character is one of those included within the square brackets.
[^agd] - the character is not one of those included within the square brackets.
[c-f] - the dash within the square brackets operates as a range. In this case it means either the letters c, d, e or f.
() - allows us to group several characters to behave as one.
| (pipe symbol) - the logical OR operation.
^ - matches the beginning of the line.
$ - matches the end of the line.
Network
show
ip a # show all interfaces
ip addr # show all interfaces
ip addr show dev ens160 # show only ens160
temporary config
ip addr add 192.168.1.1/24 dev ens160
ip addr del 192.168.1.1/24 dev ens160
remove
ip addr flush dev ens160 # remove an IP before re-assignment
UP/DOWN NIC # just like enable/disable under the windows
ip link set dev ens160 up
ip link set dev ens160 down
Permanent config
sudo vim /etc/network/interfaces
auto ens160
iface ens160 inet static/dhcp/dynamic
address 10.25.1.50
netmask 255.255.255.0
dns-nameservers 8.8.8.8 10.50.1.82
gatway 192.168.1.1
metric 0
Restart networking
systemctl restart networking
other
sudo lshw
sudo lshw -short
sudo lshw -short -class <type>
memory
network
processor
disk
arp # list ARP cache
arp -s <ipaddr> <macaddress> # add new to arp
arp -d <ipaddr>
arp -d <macaddress>
ethtool <interface> # list general hardware information
ethtool -i <interface> # list hardward device driver information
ping # check network connection
traceroute # trace packet journey
netstat #network connection information
-a # print all
-l # print which ports are listening
-s # print connection statistics
-t/-u # print only TCP/UDP connections
tcpdump #network packet information