amosli@amosli-pc:~/learn$ mkdir dir
amosli@amosli-pc:~/learn/dir$ mkdir folder
amosli@amosli-pc:~/learn/dir$ ls
folder

amosli@amosli-pc:~/learn/dir$ mkdir --help
Usage: mkdir [OPTION]... DIRECTORY...
Create the DIRECTORY(ies), if they do not already exist.Mandatory arguments to long options are mandatory for short options too.-m, --mode=MODE   set file mode (as in chmod), not a=rwx - umask-p, --parents     no error if existing, make parent directories as needed-v, --verbose     print a message for each created directory-Z, --context=CTX  set the SELinux security context of each createddirectory to CTX--help     display this help and exit--version  output version information and exitReport mkdir bugs to bug-coreutils@gnu.org
GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
For complete documentation, run: info coreutils 'mkdir invocation'

mkdir [OPTION]... DIRECTORY...

amosli@amosli-pc:~/learn/dir/folder$ mkdir par
#可不可以直接创那child/grand/目录？
amosli@amosli-pc:~/learn/dir/folder$ mkdir par/child/grand
mkdir: cannot create directory `par/child/grand': No such file or directory #答案是不可以
amosli@amosli-pc:~/learn/dir/folder$ mkdir par/child/
amosli@amosli-pc:~/learn/dir/folder$ mkdir par/child/grand
#创建完成
amosli@amosli-pc:~/learn/dir/folder$ cd par/child/grand/
amosli@amosli-pc:~/learn/dir/folder/par/child/grand$ 

amosli@amosli-pc:~/learn/dir/folder$ ls
par
amosli@amosli-pc:~/learn/dir/folder$ rm -rf *
amosli@amosli-pc:~/learn/dir/folder$ ls

amosli@amosli-pc:~/learn/dir/folder$ mkdir -p par/child/grand
amosli@amosli-pc:~/learn/dir/folder$ cd par/child/grand/
amosli@amosli-pc:~/learn/dir/folder/par/child/grand$ 

amosli@amosli-pc:~/learn/dir/folder$ rm -rf *　＃删除目录
amosli@amosli-pc:~/learn/dir/folder$ mkdir -v -m 775 par　
mkdir: created directory `par'
amosli@amosli-pc:~/learn/dir/folder$ ll
total 12
drwxrwxr-x 3 amosli amosli 4096 12月 26 22:57 ./
drwxrwxr-x 3 amosli amosli 4096 12月 26 22:33 ../
drwxrwxr-x 2 amosli amosli 4096 12月 26 22:57 par/
amosli@amosli-pc:~/learn/dir/folder$ 

amosli@amosli-pc:~/learn/dir/folder/par$ touch --help
Usage: touch [OPTION]... FILE...
Update the access and modification times of each FILE to the current time.A FILE argument that does not exist is created empty, unless -c or -h
is supplied.A FILE argument string of - is handled specially and causes touch to
change the times of the file associated with standard output.Mandatory arguments to long options are mandatory for short options too.-a                     change only the access time-c, --no-create        do not create any files-d, --date=STRING      parse STRING and use it instead of current time-f                     (ignored)-h, --no-dereference   affect each symbolic link instead of any referencedfile (useful only on systems that can change thetimestamps of a symlink)-m                     change only the modification time-r, --reference=FILE   use this file's times instead of current time-t STAMP               use [[CC]YY]MMDDhhmm[.ss] instead of current time--time=WORD            change the specified time:WORD is access, atime, or use: equivalent to -aWORD is modify or mtime: equivalent to -m--help     display this help and exit--version  output version information and exitNote that the -d and -t options accept different time-date formats.Report touch bugs to bug-coreutils@gnu.org
GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
For complete documentation, run: info coreutils 'touch invocation'

touch [OPTION]... FILE...

 　－a 改变档案的读取时间记录。－m 改变档案的修改时间记录。－c 假如目的档案不存在，不会建立新的档案。与 --no-create 的效果一样。   -h ,不干扰引用 影响每个符号链接，而不是所有参考文件（只适用于系统的改变一个符号，时间戳）－f 不会执行实际操作，是为了与其他 unix 系统的相容性而保留。－r 使用参考档的时间记录，与 --file 的效果一样。－d 设定时间与日期，可以使用各种不同的格式。－t 设定档案的时间记录，格式与 date 指令相同。[[CC]YY]MMDDhhmm[.SS]，CC为年数中的前两位，即”世纪数”;YY为年数的后两位，即某世纪中的年数.如果不给出CC的值，则linux中touch命令参数将把年数CCYY限定在1969--2068之内.MM为月数，DD为天将把年数CCYY限定在1969--2068之内.MM为月数，DD为天数，hh 为小时数(几点)，mm为分钟数，SS为秒数.此处秒的设定范围是0--61，这样可以处理闰秒.这些数字组成的时间是环境变量TZ指定的时区中的一个时间.由于系统的限制，早于1970年1月1日的时间是错误的.--no-create 不会建立新档案。--help 列出帮助信息--version 列出版本信息

amosli@amosli-pc:~/learn/dir/folder/par$ touch  a.txt
amosli@amosli-pc:~/learn/dir/folder/par$ ls -l
total 0
-rw-rw-r-- 1 amosli amosli 0 12月 26 23:07 a.txt

amosli@amosli-pc:~/learn/dir/folder/par$ touch -m a.txt
amosli@amosli-pc:~/learn/dir/folder/par$ ls -l
total 0
-rw-rw-r-- 1 amosli amosli 0 12月 26 23:09 a.txt

amosli@amosli-pc:~/learn/dir/folder/par$ touch -t 201812262315.34 b.txt
amosli@amosli-pc:~/learn/dir/folder/par$ ll
total 8
drwxrwxr-x 2 amosli amosli 4096 12月 26 23:24 ./
drwxrwxr-x 3 amosli amosli 4096 12月 26 22:57 ../
-rw-rw-r-- 1 amosli amosli    0 12月 26 23:19 a.txt
-rw-rw-r-- 1 amosli amosli    0 12月 26  2018 b.txt

＃将 file 的时间记录改变成与 referencefile 一样。
touch -r referencefile file

amosli@amosli-pc:~/learn/dir/folder/par$ touch -r b.txt  a.txt
amosli@amosli-pc:~/learn/dir/folder/par$ ls -l
total 0
-rw-rw-r-- 1 amosli amosli 0 12月 26  2018 a.txt
-rw-rw-r-- 1 amosli amosli 0 12月 26  2018 b.txt