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记录自己的学习过程
一、Linux中的文件类型
Linux中万物皆文件
在使用ls -l时，展示出来文件的详细信息时，第一个字符所表示的含义：
[root@my-rhel ~]
total 4
-rw-------. 1 root root 1766 Aug 4 13:34 anaconda-ks.cfg
drwxr-xr-x. 2 root root 51 Aug 5 11:55 myMp4
[root@my-rhel ~]
[root@my-rhel /]
[root@my-rhel dev]
total 0
crw-r--r--. 1 root root 10, 235 Aug 6 17:20 autofs
drwxr-xr-x. 2 root root 160 Aug 6 17:20 block
drwxr-xr-x. 2 root root 60 Aug 6 17:20 bsg
drwxr-xr-x. 3 root root 60 Aug 6 17:20 bus
lrwxrwxrwx. 1 root root 3 Aug 6 17:20 cdrom -> sr0
drwxr-xr-x. 2 root root 2900 Aug 6 17:20 char
crw-------. 1 root root 5, 1 Aug 6 17:20 console
lrwxrwxrwx. 1 root root 11 Aug 6 17:20 core -> /proc/kcore
drwxr-xr-x. 4 root root 80 Aug 6 17:20 cpu
crw-------. 1 root root 10, 62 Aug 6 17:20 cpu_dma_latency
drwxr-xr-x. 7 root root 140 Aug 6 17:20 disk
brw-rw----. 1 root disk 253, 0 Aug 6 17:20 dm-0
brw-rw----. 1 root disk 253, 1 Aug 6 17:20 dm-1
crw-rw----. 1 root audio 14, 9 Aug 6 17:20 dmmidi
drwxr-xr-x. 3 root root 100 Aug 6 17:20 dri
- 或者 f，表示的是普通文件d 是directory，表示的是目录文件l 是link，表示的是连接文件，类似于Windows中的快捷方式，当这个连接文件所指向的具体的文件被删除时，这个连接文件也随之消失b 是block，表示的是块设备文件 ------ 硬盘c 是character，表示的是字符设备文件 ------ 终端和键盘p 是pipe，表示的是管道文件s 是socket，表示的是套接字文件
二、查看指令的类型
使用type 命令 查看该命令的类型
[root@my-rhel bin]
cd is a shell builtin
[root@my-rhel bin]
date is /usr/bin/date
[root@my-rhel bin]
yum is /usr/bin/yum
cd is a shell builtin 出现这个意思就是 该指令是内部指令
date is /usr/bin/date 出现这个意思就是 该指令是内部指令
有时候只使用type时会出现例外情况：
[root@my-rhel ~]
rm is aliased to `rm -i'
这里只打印出来rm is aliased to 'rm -i'
alias 的意思是 别名
我们在type 后面加上 -a 可以查看详细一点
[root@my-rhel ~]
rm is aliased to `rm -i'
rm is /usr/bin/rm
三、man 和 help
man
使用方法：man 命令
你可以使用man man来查看man怎么用 哈哈哈哈哈
NAME 命令名称及功能简要说明
SYNOPSIS 用法说明，包括可用的选项
DESCRIPTION 命令功能的详细说明，可能包括每一个选项的意义
OPTIONS 说明每一项的意义
FILES 此命令相关的配置文件
EXAMPLES 使用示例
SEE ALSO 另外参照
操作方法：
例如：man ls 后
查看时需要翻屏：
向后翻一屏：space(空格键) 向前翻一屏：b
向后翻一行：Enter(回车键) 向前翻一行：k
查看时需要查找：
/关键词 向后查找 n：下一个
?关键词 向前查找 N：前一个
[root@my-rhel ~]
LS(1) User Commands LS(1)
NAME
ls - list directory contents
SYNOPSIS
ls [OPTION]... [FILE]...
DESCRIPTION
List information about the FILEs (the current directory by
default). Sort entries alphabetically if none of -cftuvSUX nor
--sort is specified.
Mandatory arguments to long options are mandatory for short options
too.
-a, --all
do not ignore entries starting with .
-A, --almost-all
do not list implied . and ..
--author
with -l, print the author of each file
-b, --escape
print C-style escapes for nongraphic characters
--block-size=SIZE
with -l, scale sizes by SIZE when printing them; e.g.,
'--block-size=M'; see SIZE format below
-B, --ignore-backups
do not list implied entries ending with ~
-c with -lt: sort by, and show, ctime (time of last modifica‐
tion of file status information); with -l: show ctime and
sort by name; otherwise: sort by ctime, newest first
-C list entries by columns
--color[=WHEN]
colorize the output; WHEN can be 'always' (default if omit‐
ted), 'auto', or 'never'; more info below
-d, --directory
list directories themselves, not their contents
-D, --dired
generate output designed for Emacs' dired mode
-f do not sort, enable -aU, disable -ls --color
-F, --classify
append indicator (one of */=>@|) to entries
--file-type
likewise, except do not append '*'
--format=WORD
across -x, commas -m, horizontal -x, long -l, single-column
-1, verbose -l, vertical -C
--full-time
like -l --time-style=full-iso
-g like -l, but do not list owner
--group-directories-first
group directories before files;
can be augmented with a --sort option, but any use of
--sort=none (-U) disables grouping
-G, --no-group
in a long listing, don't print group names
-h, --human-readable
with -l and -s, print sizes like 1K 234M 2G etc.
--si likewise, but use powers of 1000 not 1024
-H, --dereference-command-line
follow symbolic links listed on the command line
--dereference-command-line-symlink-to-dir
follow each command line symbolic link
that points to a directory
--hide=PATTERN
do not list implied entries matching shell PATTERN (overrid‐
den by -a or -A)
--hyperlink[=WHEN]
hyperlink file names; WHEN can be 'always' (default if omit‐
ted), 'auto', or 'never'
--indicator-style=WORD
append indicator with style WORD to entry names: none
(default), slash (-p), file-type (--file-type), classify
(-F)
-i, --inode
print the index number of each file
-I, --ignore=PATTERN
do not list implied entries matching shell PATTERN
-k, --kibibytes
default to 1024-byte blocks for disk usage; used only with
-s and per directory totals
-l use a long listing format
-L, --dereference
when showing file information for a symbolic link, show
information for the file the link references rather than for
the link itself
-m fill width with a comma separated list of entries
-n, --numeric-uid-gid
like -l, but list numeric user and group IDs
-N, --literal
print entry names without quoting
-o like -l, but do not list group information
-p, --indicator-style=slash
append / indicator to directories
-q, --hide-control-chars
print ? instead of nongraphic characters
--show-control-chars
show nongraphic characters as-is (the default, unless pro‐
gram is 'ls' and output is a terminal)
-Q, --quote-name
enclose entry names in double quotes
--quoting-style=WORD
use quoting style WORD for entry names: literal, locale,
shell, shell-always, shell-escape, shell-escape-always, c,
escape (overrides QUOTING_STYLE environment variable)
-r, --reverse
reverse order while sorting
-R, --recursive
list subdirectories recursively
-s, --size
print the allocated size of each file, in blocks
-S sort by file size, largest first
--sort=WORD
sort by WORD instead of name: none (-U), size (-S), time
(-t), version (-v), extension (-X)
--time=WORD
with -l, show time as WORD instead of default modification
time: atime or access or use (-u); ctime or status (-c);
also use specified time as sort key if --sort=time (newest
first)
--time-style=TIME_STYLE
time/date format with -l; see TIME_STYLE below
-t sort by modification time, newest first
-T, --tabsize=COLS
assume tab stops at each COLS instead of 8
-u with -lt: sort by, and show, access time; with -l: show
access time and sort by name; otherwise: sort by access
time, newest first
-U do not sort; list entries in directory order
-v natural sort of (version) numbers within text
-w, --width=COLS
set output width to COLS. 0 means no limit
-x list entries by lines instead of by columns
-X sort alphabetically by entry extension
-Z, --context
print any security context of each file
-1 list one file per line. Avoid '\n' with -q or -b
--help display this help and exit
--version
output version information and exit
The SIZE argument is an integer and optional unit (example: 10K is
10*1024). Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,...
(powers of 1000).
The TIME_STYLE argument can be full-iso, long-iso, iso, locale, or
+FORMAT. FORMAT is interpreted like in date(1). If FORMAT is FOR‐
MAT1<newline>FORMAT2, then FORMAT1 applies to non-recent files and
FORMAT2 to recent files. TIME_STYLE prefixed with 'posix-' takes
effect only outside the POSIX locale. Also the TIME_STYLE environ‐
ment variable sets the default style to use.
Using color to distinguish file types is disabled both by default
and with --color=never. With --color=auto, ls emits color codes
only when standard output is connected to a terminal. The LS_COL‐
ORS environment variable can change the settings. Use the dircol‐
ors command to set it.
Exit status:
0 if OK,
1 if minor problems (e.g., cannot access subdirectory),
2 if serious trouble (e.g., cannot access command-line argu‐
ment).
AUTHOR
Written by Richard M. Stallman and David MacKenzie.
REPORTING BUGS
GNU coreutils online help: <https://www.gnu.org/software/core‐
utils/>
Report ls translation bugs to <https://translationpro‐
ject.org/team/>
COPYRIGHT
Copyright ? 2018 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
Full documentation at: <https://www.gnu.org/software/coreutils/ls>
or available locally via: info '(coreutils) ls invocation'
help
当我们遇到某个命令，不知道怎么用时，就可以使用这个help，用法：命令 --help
[root@my-rhel ~]
type: type [-afptP] name [name ...]
Display information about command type.
For each NAME, indicate how it would be interpreted if used as a
command name.
Options:
-a display all locations containing an executable named NAME;
includes aliases, builtins, and functions, if and only if
the `-p' option is not also used
-f suppress shell function lookup
-P force a PATH search for each NAME, even if it is an alias,
builtin, or function, and returns the name of the disk file
that would be executed
-p returns either the name of the disk file that would be executed,
or nothing if `type -t NAME' would not return `file'
-t output a single word which is one of `alias', `keyword',
`function', `builtin', `file' or `', if NAME is an alias,
shell reserved word, shell function, shell builtin, disk file,
or not found, respectively
Arguments:
NAME Command name to be interpreted.
Exit Status:
Returns success if all of the NAMEs are found; fails if any are not found.
总结
man 和 help 里面全是英文，需要一定的词汇量，遇到不会的词，积极去查，多积累
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