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[dywang@dywHome2 ~]$ date --help
Usage: date [OPTION]... [+FORMAT]
or: date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]
Display the current time in the given FORMAT, or set the system date.
-d, --date=STRING display time described by STRING, not `now'
## 以 STRING 格式顯示時間，不是'現在'時間。
-f, --file=DATEFILE like --date once for each line of DATEFILE
-r, --reference=FILE display the last modification time of FILE
-R, --rfc-2822 output date and time in RFC 2822 format
--rfc-3339=TIMESPEC output date and time in RFC 3339 format.
TIMESPEC=`date', `seconds', or `ns' for
date and time to the indicated precision.
-s, --set=STRING set time described by STRING
## 以 STRING 格式設定時間。
-u, --utc, --universal print or set
## 顯示目前的格林威治時間。
--help display this help and exit
--version output version information and exit
FORMAT controls the output. The only valid option for the second form
specifies Coordinated Universal Time. Interpreted sequences are:
%% a literal %
%a locale's abbreviated weekday name (e.g., Sun)
%A locale's full weekday name (e.g., Sunday)
%b locale's abbreviated month name (e.g., Jan)
%B locale's full month name (e.g., January)
%c locale's date and time (e.g., Thu Mar 3 23:05:25 2005)
%C century; like %Y, except omit last two digits (e.g., 21)
%d day of month (e.g, 01)
%D date; same as %m/%d/%y
%e day of month, space padded; same as %_d
%F full date; same as %Y-%m-%d
%g last two digits of year of ISO week number (see %G)
%G year of ISO week number (see %V); normally useful only with %V
%h same as %b
%H hour (00..23)
%I hour (01..12)
%j day of year (001..366)
%k hour ( 0..23)
%l hour ( 1..12)
%m month (01..12)
%M minute (00..59)
%n a newline
%N nanoseconds (000000000..999999999)
%p locale's equivalent of either AM or PM; blank if not known
%P like %p, but lower case
%r locale's 12-hour clock time (e.g., 11:11:04 PM)
%R 24-hour hour and minute; same as %H:%M
%s seconds since 1970-01-01 00:00:00 UTC
%S second (00..60)
%t a tab
%T time; same as %H:%M:%S
%u day of week (1..7); 1 is Monday
%U week number of year, with Sunday as first day of week (00..53)
%V ISO week number, with Monday as first day of week (01..53)
%w day of week (0..6); 0 is Sunday
%W week number of year, with Monday as first day of week (00..53)
%x locale's date representation (e.g., 12/31/99)
%X locale's time representation (e.g., 23:13:48)
%y last two digits of year (00..99)
%Y year
%z +hhmm numeric timezone (e.g., -0400)
%:z +hh:mm numeric timezone (e.g., -04:00)
%::z +hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z alphabetic time zone abbreviation (e.g., EDT)
時間方面 :
%% : 印出 %
%n : 下一行
%t : 跳格
%H : 小時(00..23)
%I : 小時(01..12)
%k : 小時(0..23)
%l : 小時(1..12)
%M : 分鐘(00..59)
%p : 顯示本地 AM 或 PM
%r : 直接顯示時間 (12 小時制，格式為 hh:mm:ss [AP]M)
%s : 以 1970 年 1 月 1 日 00:00:00 UTC 到目前為止的秒數
%S : 秒(00..61)
%T : 直接顯示時間 (24 小時制)
%X : 相當於 %H:%M:%S
%Z : 顯示時區
日期方面 :
%a : 星期幾 (Sun..Sat)
%A : 星期幾 (Sunday..Saturday)
%b : 月份 (Jan..Dec)
%B : 月份 (January..December)
%c : 直接顯示日期與時間
%d : 日 (01..31)
%D : 直接顯示日期 (mm/dd/yy)
%h : 同 %b
%j : 一年中的第幾天 (001..366)
%m : 月份 (01..12)
%U : 一年中的第幾周 (00..53) (以 Sunday 為一周的第一天的情形)
%w : 一周中的第幾天 (0..6)
%W : 一年中的第幾周 (00..53) (以 Monday 為一周的第一天的情形)
%x : 直接顯示日期 (mm/dd/yy)
%y : 年份的最後兩位數字 (00.99)
%Y : 完整年份 (0000..9999)
By default, date pads numeric fields with zeroes.
The following optional flags may follow `%':
- (hyphen) do not pad the field
_ (underscore) pad with spaces
0 (zero) pad with zeros
^ use upper case if possible
# use opposite case if possible
After any flags comes an optional field width, as a decimal number;
then an optional modifier, which is either
E to use the locale's alternate representations if available, or
O to use the locale's alternate numeric symbols if available.
Report bugs to <bug-coreutils@gnu.org>.
[dywang@mdk-dyw ~]$ date +%Y/%m/%d
2006/10/05
[dywang@dywOffice ~]$ date +%H:%M
09:37
[dywang@dywHome2 ~]$ # 顯示時間後跳行，再顯示目前日期:
[dywang@dywHome2 ~]$ date '+%T%n%D'
18:16:19
08/01/09
[dywang@dywHome2 ~]$ # 顯示月份與日
[dywang@dywHome2 ~]$ date '+%B %d'
August 01
[dywang@dywHome2 ~]$ # 明天
[dywang@dywHome2 ~]$ date --date="1 day" +%F
2009-08-02
[dywang@dywHome2 ~]$ # 後天
[dywang@dywHome2 ~]$ date --date="2 day" +%F
2009-08-03
[dywang@dywHome2 ~]$ # 昨天
[dywang@dywHome2 ~]$ date --date="1 day ago" +%F
2009-07-31
[dywang@dywHome2 ~]$ # 前天
[dywang@dywHome2 ~]$ date --date="2 day ago" +%F
2009-07-30
[dywang@dywHome2 ~]$ # 2009-1-1 的前一天
[dywang@dywHome2 ~]$ date --date="2009-1-1 1 day ago" +%F
2008-12-31
[dywang@dywHome2 ~]$ # 2008-2-28 的後一天
[dywang@dywHome2 ~]$ date --date="2008-2-28 1 day" +%F
2008-02-29
[dywang@dywHome2 ~]$ # 2008-2-28的兩個月前
[dywang@dywHome2 ~]$ date --date="2008-2-28 2 month ago" +%F
2007-12-28
[root@dywHome2 ~]# # 設定時間為 12:34:56，必須以 root 身份
[root@dywHome2 ~]# date -s '12:34:56'
Sat Aug 1 12:34:56 CST 2009
[dywang@dywHome2 ~]$ cal --help
cal: invalid option -- -
usage: cal [-13smjyV] [[month] year]
[dywang@mdk-dyw ~]$ man cal
CAL(1) BSD General Commands Manual CAL(1)
NAME
cal - displays a calendar
SYNOPSIS
cal [-smjy13] [[month] year]
DESCRIPTION
Cal displays a simple calendar. If arguments are not specified, the cur-
rent month is displayed. The options are as follows:
-1 Display single month output. (This is the default.)
-3 Display prev/current/next month output.
-s Display Sunday as the first day of the week. (This is the
default.)
-m Display Monday as the first day of the week.
-j Display Julian dates (days one-based, numbered from January 1).
-y Display a calendar for the current year.
A single parameter specifies the year (1 - 9999) to be displayed; note
the year must be fully specified: “cal 89” will not display a calendar
for 1989. Two parameters denote the month (1 - 12) and year. If no
parameters are specified, the current month's calendar is displayed.
A year starts on Jan 1.
The Gregorian Reformation is assumed to have occurred in 1752 on the 3rd
of September. By this time, most countries had recognized the reforma-
tion (although a few did not recognize it until the early 1900's.) Ten
days following that date were eliminated by the reformation, so the cal-
endar for that month is a bit unusual.
HISTORY
A cal command appeared in Version 6 AT&T UNIX.
OTHER VERSIONS
Several much more elaborate versions of this program exist, with support
for colors, holidays, birthdays, reminders and appointments, etc. For
example, try the cal from http://home.sprynet.com/~cbagwell/projects.html
or GNU gcal.
BSD June 6, 1993 BSD
[dywang@dywHome2 ~]$ cal
August 2009
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
[dywang@dywHome2 ~]$ cal -1
August 2009
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
[dywang@dywHome2 ~]$ cal -3
July 2009 August 2009 September 2009
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 2 3 4 1 1 2 3 4 5
5 6 7 8 9 10 11 2 3 4 5 6 7 8 6 7 8 9 10 11 12
12 13 14 15 16 17 18 9 10 11 12 13 14 15 13 14 15 16 17 18 19
19 20 21 22 23 24 25 16 17 18 19 20 21 22 20 21 22 23 24 25 26
26 27 28 29 30 31 23 24 25 26 27 28 29 27 28 29 30
30 31
[dywang@dywHome2 ~]$ cal -s
August 2009
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
[dywang@dywHome2 ~]$ cal -m
August 2009
Mo Tu We Th Fr Sa Su
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31
[dywang@dywHome2 ~]$ cal -j
August 2009
Sun Mon Tue Wed Thu Fri Sat
213
214 215 216 217 218 219 220
221 222 223 224 225 226 227
228 229 230 231 232 233 234
235 236 237 238 239 240 241
242 243
[dywang@dywHome2 ~]$ cal -y
2009
January February March
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 2 3 1 2 3 4 5 6 7 1 2 3 4 5 6 7
4 5 6 7 8 9 10 8 9 10 11 12 13 14 8 9 10 11 12 13 14
11 12 13 14 15 16 17 15 16 17 18 19 20 21 15 16 17 18 19 20 21
18 19 20 21 22 23 24 22 23 24 25 26 27 28 22 23 24 25 26 27 28
25 26 27 28 29 30 31 29 30 31
April May June
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 2 3 4 1 2 1 2 3 4 5 6
5 6 7 8 9 10 11 3 4 5 6 7 8 9 7 8 9 10 11 12 13
12 13 14 15 16 17 18 10 11 12 13 14 15 16 14 15 16 17 18 19 20
19 20 21 22 23 24 25 17 18 19 20 21 22 23 21 22 23 24 25 26 27
26 27 28 29 30 24 25 26 27 28 29 30 28 29 30
31
July August September
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 2 3 4 1 1 2 3 4 5
5 6 7 8 9 10 11 2 3 4 5 6 7 8 6 7 8 9 10 11 12
12 13 14 15 16 17 18 9 10 11 12 13 14 15 13 14 15 16 17 18 19
19 20 21 22 23 24 25 16 17 18 19 20 21 22 20 21 22 23 24 25 26
26 27 28 29 30 31 23 24 25 26 27 28 29 27 28 29 30
30 31
October November December
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 2 3 1 2 3 4 5 6 7 1 2 3 4 5
4 5 6 7 8 9 10 8 9 10 11 12 13 14 6 7 8 9 10 11 12
11 12 13 14 15 16 17 15 16 17 18 19 20 21 13 14 15 16 17 18 19
18 19 20 21 22 23 24 22 23 24 25 26 27 28 20 21 22 23 24 25 26
25 26 27 28 29 30 31 29 30 27 28 29 30 31
[dywang@dywHome2 ~]$ cal -m3 9 2012
August 2012 September 2012 October 2012
Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su
1 2 3 4 5 1 2 1 2 3 4 5 6 7
6 7 8 9 10 11 12 3 4 5 6 7 8 9 8 9 10 11 12 13 14
13 14 15 16 17 18 19 10 11 12 13 14 15 16 15 16 17 18 19 20 21
20 21 22 23 24 25 26 17 18 19 20 21 22 23 22 23 24 25 26 27 28
27 28 29 30 31 24 25 26 27 28 29 30 29 30 31
[dywang@dywHome2 ~]$ bc --help
usage: bc [options] [file ...]
-h --help print this usage and exit
-i --interactive force interactive mode
-l --mathlib use the predefine math routnes
-q --quiet don't print initial banner
-s --standard non-standard bc constructs are errors
-w --warn warn about non-standard bc constructs
-v --version print version information and exit
[dywang@mdk-dyw ~]$ man bc
## 以下只整理使用重點，完整使用手冊請自行參考 man bc。
NUMBERS
...省略... The length is the total number of significant decimal digits
in a number and the scale is the total number of decimal digits after
the decimal point. For example:
.000001 has a length of 6 and scale of 6.
1935.000 has a length of 7 and a scale of 3.
VARIABLES
...省略... All letters must be lower case.
...省略... The default value of scale is 0.
COMMENTS
Comments in bc start with the characters /* and end with the characters
*/. ...省略... A single line comment starts at a # character
and continues to the next end of the line. ...省略...
EXPRESSIONS
...省略...
- expr The result is the negation of the expression.
++ var The variable is incremented by one and the new value is the
result of the expression.
-- var The variable is decremented by one and the new value is the
result of the expression.
var ++ The result of the expression is the value of the variable and
then the variable is incremented by one.
var -- The result of the expression is the value of the variable and
then the variable is decremented by one.
expr + expr
The result of the expression is the sum of the two expressions.
expr - expr
The result of the expression is the difference of the two
expressions.
expr * expr
The result of the expression is the product of the two expres-
sions.
expr / expr
The result of the expression is the quotient of the two expres-
sions. The scale of the result is the value of the variable
scale.
expr % expr
The result of the expression is the "remainder". ...省略...
expr ^ expr
The result of the expression is the value of the first raised to
the second. The second expression must be an integer. ...省略...
( expr )
This alters the standard precedence to force the evaluation of
the expression.
var = expr
The variable is assigned the value of the expression.
var <op>= expr
This is equivalent to "var = var <op> expr" ...省略...
...省略... relational operators are:
expr1 < expr2
The result is 1 if expr1 is strictly less than expr2.
expr1 %*<== expr2*)
The result is 1 if expr1 is less than or equal to expr2.
expr1 > expr2
The result is 1 if expr1 is strictly greater than expr2.
expr1 >= expr2
The result is 1 if expr1 is greater than or equal to expr2.
expr1 == expr2
The result is 1 if expr1 is equal to expr2.
expr1 != expr2
The result is 1 if expr1 is not equal to expr2.
...省略... The boolean operators are:
!expr The result is 1 if expr is 0.
expr && expr
The result is 1 if both expressions are non-zero.
expr || expr
The result is 1 if either expression is non-zero.
The expression precedence is as follows: (lowest to highest)
|| operator, left associative
&& operator, left associative
! operator, nonassociative
Relational operators, left associative
Assignment operator, right associative
+ and - operators, left associative
*, / and % operators, left associative
^ operator, right associative
unary - operator, nonassociative
++ and -- operators, nonassociative
...省略...
length ( expression )
The value of the length function is the number of significant
digits in the expression.
read ( )
The read function (an extension) will read a number from the
standard input, ...省略...
scale ( expression )
The value of the scale function is the number of digits after
the decimal point in the expression.
sqrt ( expression )
The value of the sqrt function is the square root of the expres-
sion. If the expression is negative, a run time error is gener-
ated.
STATEMENTS
...省略...
{ statement_list }
This is the compound statement. It allows multiple statements
to be grouped together for execution.
if ( expression ) statement1 [else statement2]
...省略...
If the expression is non-zero, statement1 is executed. If
statement2 is present and the value of the expression is 0, then
statement2 is executed.
while ( expression ) statement
The while statement will execute the statement while the expres-
sion is non-zero. ...省略...
for ( [expression1] ; [expression2] ; [expression3] ) statement
The for statement controls repeated execution of the statement.
...省略...
break This statement causes a forced exit of the most recent enclosing
while statement or for statement.
continue
The continue statement (an extension) causes the most recent
enclosing for statement to start the next iteration.
halt ...省略...
return Return the value 0 from a function. (See the section on func-
tions.)
return ( expression )
Return the value of the expression from a function. ...省略...
PSEUDO STATEMENTS
...省略...
FUNCTIONS
...省略... A function is defined as follows:
define name ( parameters ) { newline
auto_list statement_list }
A function call is just an expression of the form "name(parameters)".
The auto_list is an optional list of variables that are for "local"
use. The syntax of the auto list (if present) is "auto name, ... ;".
...省略... The variables are then initialized to zero ...省略...
For example, the following definitions are legal.
define d (n) { return (2*n); }
define d (n)
{ return (2*n); }
MATH LIBRARY
...省略...
s (x) The sine of x, x is in radians.
c (x) The cosine of x, x is in radians.
a (x) The arctangent of x, arctangent returns radians.
l (x) The natural logarithm of x.
e (x) The exponential function of raising e to the value x.
j (n,x)
The bessel function of integer order n of x.
EXAMPLES
...省略...
範例：定義階層 x! 函數
define f (x) {
if (x %*<== 1) return (1);*)
return (f(x-1) * x);
}
READLINE AND LIBEDIT OPTIONS
...省略...
DIFFERENCES
...省略...
LIMITS
...省略...
ENVIRONMENT VARIABLES
...省略...
DIAGNOSTICS
...省略...
BUGS
...省略...
AUTHOR
Philip A. Nelson
philnelson@acm.org
ACKNOWLEDGEMENTS
The author would like to thank Steve Sommars (Steve.Sommars@att.com)
for his extensive help in testing the implementation. Many great sug-
gestions were given. This is a much better product due to his involve-
ment.
. bc(1)
[dywang@mdk-dyw ~]$ bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.
(3+4)^2
49
4/3
1
scale=3
4/3
1.333
sacle=0
x=read()
100
for(i=0;i<x;i++) {
total+=(i+1)
}
total
5050
var1=10
var2=var1++
var1;var2
11
10
var2=++var1
var1;var2
12
12
define f (x) {
if (x %*<== 1) return (1);*)
return (f(x-1) * x);
}
f(4)
24