One,
The first is the date command
%Command option arguments
Command to get help through the man command, then found date has two functions:
1, check the time, the display format can achieve what you want by blending options
2, set the time
% As well as internal command help command, external command command help.
% Linux shell internal command with an external command What are the differences and how to identify https://www.cnblogs.com/gavinpan/p/11248279.html
% Type displays the type of command.
% Builtin built
two,
Man: manual command manual
Sub-chapter manual requires%
1, the user command (/ bin, / usr / bin, / usr / local / bin)
2, the system call
3, library users
4, special file (device file)
5, file format
6, game
7. Miscellaneous (Miscellaneous)
8, management commands (/sbin,/usr/sbin./usr/loacl/sbin)
% Whatis command can be viewed through the first few chapters belonging to this command
How help documentation% after the man command (if the English ten I think is OK),
NAME: command name and Features
SYNOPSIS: Usage Notes, including the options available
DESCRIPTION: detailed description of the command function, and may include the meaning of each option
FILES: This command related configuration files
BUGS：
EXAMPLES: Example of use
SEE ALSO: additional reference
% Used button when viewing the document:
Scroll:
Turned back one screen: SPACE
The flip ahead a screen: b
Backward line: ENTER
The flip ahead a row: k
Find:
/ KEYWORD: back
n: Next
N: previous
? KEYWORD: forward
n: Next
N: previous
q: quit
Third, the configuration related to some open source projects can use google to search
%apache hadoop
% With respect to time there is a command hwclock:
-s, --hctosys
Set the System Time from the Hardware Clock.Also set the kernel's timezone value to the local timezone as indicated by the TZ environment variable and/or /usr/share/zone‐info, as tzset(3) would interpret them. The obsolete tz_dsttime field of the kernel's timezone value is set to DST_NONE.(For details on what this field used to mean, see settimeofday(2).)This is a good option to use in one of the system startup scripts.
-w, --systohc
Set the Hardware Clock to the current System Time.
Hardware Hardware
four,
% Cal: display a calendar with the
Fifth, work
Exercise:
1, echo command is internal or external command?
[root@linuxprobe ~]# type echo
echo is a shell builtin
2, its role?
[root@linuxprobe ~]# help echo | [root@linuxprobe ~]# man help
% Output display standard in a new line in
3, how to display "The year is 2013. Today is 26." two lines?
[root@linuxprobe ~]# echo -e "the year os 2020.\ntoday is 25"
the year os 2020.
today is 25
Escape, escape
Exercise:
1, printf command is internal or external command?
[root@linuxprobe ~]# type printf
printf is a shell builtin
2, its role?
Formats and prints ARGUMENTS under control of the FORMAT.
Format and print ARGUMENTS under control of FORMAT
3, how to display "The year is 2013. Today is 26." two lines?
[root@linuxprobe ~]# printf "the year is 2013.today is 25"
the year is 2013.today is 25[root@linuxprobe ~]# printf "the year is 2013.\ntoday isthe year is 2013.
today is 25
4, file commands and their usage.
[root@linuxprobe ~]# type file
file is /usr/bin/file
[root@linuxprobe ~]# file --help
Usage: file [OPTION...] [FILE...]
Determine type of FILEs.
--help display this help and exit
-v, --version output version information and exit
-m, --magic-file LIST use LIST as a colon-separated list of magic
number files
-z, --uncompress try to look inside compressed files
-b, --brief do not prepend filenames to output lines
-c, --checking-printout print the parsed form of the magic file, use in
conjunction with -m to debug a new magic file
before installing it
-e, --exclude TEST exclude TEST from the list of test to be
performed for file. Valid tests are:
ascii, apptype, compress, elf, soft, tar, tokens, troff
-f, --files-from FILE read the filenames to be examined from FILE
-F, --separator STRING use string as separator instead of `:'
-i, --mime output MIME type strings (--mime-type and
--mime-encoding)
--apple output the Apple CREATOR/TYPE
--mime-type output the MIME type
--mime-encoding output the MIME encoding
-k, --keep-going don't stop at the first match
-l, --list list magic strength
-L, --dereference follow symlinks (default)
-h, --no-dereference don't follow symlinks
-n, --no-buffer do not buffer output
-N, --no-pad do not pad output
-0, --print0 terminate filenames with ASCII NUL
-p, --preserve-date preserve access times on files
-r, --raw don't translate unprintable chars to \ooo
-s, --special-files treat special (block/char devices) files as
ordinary ones
-C, --compile compile file specified by -m
-d, --debug print debugging messages