I. Review
1, user management, rights management, install, mktemp
2, user management:
3, rights management:
mode，ownership
mode：
user
group
other
r
w
x
4, the command: install, mktemp
Two, bash and bash scripting initial characteristics
1, the terminal: the terminal attached to the interface program
GUI: KDE, GNOME, Xfce
CLI：/etc/shells
2, bash features:
a, expand the command line: ~, {}
b, command aliases: alias, unalias
c, command history: history
d, file name wildcard
e, shortcut keys: Ctrl + a, e, u, k, l
f, command completion: $ PATH
g, the path completion:
3, the characteristics of hash bash command
a, the results of the previous command to find the cache, that command hash. Note that he will only cache external command, because it is an internal command shell that comes with it is not cached, including hash myself.
[root@localhost ~]# hash hash: hash table empty [root@localhost ~]# ls /root/ anaconda-ks.cfg hello inittab [root@localhost ~]# cat /etc/fstab > /dev/null [root@localhost ~]# echo "wohaoshuai" > /dev/null [root@localhost ~]# hash hits command 1 /usr/bin/cat 1 /usr/bin/ls
b, Options
-d: Forget the position of each command has to remember
-r: forget all remembered locations
[root@localhost ~]# hash hits command 1 /usr/bin/cat 1 /usr/bin/ls [root@localhost ~]# hash -d cat [root@localhost ~]# hash hits command 1 /usr/bin/ls [root@localhost ~]# hash -r [root@localhost ~]# hash hash: hash table empty
c, corresponding to the cache storage format is: key-value
key: the search key
value: value
Third, the characteristics of the bash: Variable
1, the program: the composition of instruction data +
Instruction: provided by the program file
Data: IO devices, files, pipes, variable
Program: Algorithms + Data Structures
2, the variable name + points to memory space
3, variable assignment: name = value
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