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command_argument_count

名称

command_argument_count(3) - [SYSTEM:COMMAND LINE] 获取命令行参数的数量

Synopsis

    result = command_argument_count()

     integer function command_argument_count()

Characteristics

• the result is of default integer scalar.

说明

command_argument_count(3) returns the number of arguments passed on the command line when the containing program was invoked.

选项

无

结果

: The return value is of type default integer. It is the number of arguments passed on the command line when the program was invoked.

If there are no command arguments available or if the processor does not support command arguments, then the result has the value zero.

If the processor has a concept of a command name, the command name does not count as one of the command arguments.

示例

示例程序：

program demo_command_argument_count
implicit none
integer :: count
   count = command_argument_count()
   print *, count
end program demo_command_argument_count

样本输出：

   # the command verb does not count
   ./test_command_argument_count
       0
   # quoted strings may count as one argument
   ./test_command_argument_count count arguments
       2
   ./test_command_argument_count 'count arguments'
       1

标准

Fortran 2003

另见

get_command(3)，get_command_argument(3)

fortran-lang intrinsic descriptions (license: MIT) @urbanjost

get_command

名称

get_command(3) - [SYSTEM:COMMAND LINE] Get the entire command line invocation

Synopsis

    call get_command([command] [,length] [,status] [,errmsg])

     subroutine get_command( command ,length ,status, errmsg )

      character(len=*),intent(out),optional   :: command
      integer(kind=**),intent(out),optional   :: length
      integer(kind=**),intent(out),optional   :: status
      character(len=*),intent(inout),optional :: errmsg

Characteristics

• a kind designated as ** may be any supported kind for the type meeting the conditions described herein.

• command and errmsg are scalar character variables of default kind.

• length and status are scalar integer with a decimal exponent range of at least four.

说明

get_command(3) retrieves the entire command line that was used to invoke the program.

请注意，在命令行上键入的内容通常由 shell 处理。 shell 通常在将特殊字符和空格传递给程序之前对其进行处理。通常可以通过关闭通配符或引用命令行参数和/或更改默认字段分隔符来关闭处理，但这应该很少需要。

结果

• command

  If command is present, the entire command line that was used to invoke the program is stored into it. If the command cannot be determined, command is assigned all blanks.

• length

  If length is present, it is assigned the length of the command line. It is system-dependent as to whether trailing blanks will be counted.

  If the command length cannot be determined, a length of 0 is assigned.

• status

  If status is present, it is assigned 0 upon success of the command, -1 if command is too short to store the command line, or a positive value in case of an error.

• errmsg

  It is assigned a processor-dependent explanatory message if the command retrieval fails. Otherwise, it is unchanged.

示例

示例程序：

program demo_get_command
implicit none
integer                      :: command_line_length
character(len=:),allocatable :: command_line
   ! get command line length
   call get_command(length=command_line_length)
   ! allocate string big enough to hold command line
   allocate(character(len=command_line_length) :: command_line)
   ! get command line as a string
   call get_command(command=command_line)
   ! trim leading spaces just in case
   command_line=adjustl(command_line)
   write(*,'("OUTPUT:",a)')command_line
end program demo_get_command

结果：

     # note that shell expansion removes some of the whitespace
     # without quotes
     ./test_get_command  arguments    on command   line to   echo

     OUTPUT:./test_get_command arguments on command line to echo

     # using the bash shell with single quotes
     ./test_get_command  'arguments  *><`~[]!{}?"\'| '

     OUTPUT:./test_get_command arguments  *><`~[]!{}?"'|

标准

Fortran 2003

另见

get_command_argument(3)，command_argument_count(3)

fortran-lang intrinsic descriptions (license: MIT) @urbanjost

get_command_argument

名称

get_command_argument(3) - [SYSTEM:COMMAND LINE] 获取命令行参数

Synopsis

  call get_command_argument(number [,value] [,length] &
  & [,status] [,errmsg])

   subroutine get_command_argument( number, value, length, &
   & status ,errmsg)

    integer(kind=**),intent(in)             :: number
    character(len=*),intent(out),optional   :: value
    integer(kind=**),intent(out),optional   :: length
    integer(kind=**),intent(out),optional   :: status
    character(len=*),intent(inout),optional :: errmsg

Characteristics

• a kind designated as ** may be any supported kind for the type meeting the conditions described herein.

• number, length, and status are scalar integer with a decimal exponent range of at least four.

• value and errmsg are scalar character variables of default kind.

说明

get_command_argument(3) retrieves or queries the n-th argument that was passed on the command line to the current program execution.

There is not anything specifically stated about what an argument is but in practice the arguments are strings split on whitespace unless the arguments are quoted. IFS values (Internal Field Separators) used by common shells are typically ignored and unquoted whitespace is almost always the separator.

Shells have often expanded command arguments and spell characters before passing them to the program, so the strings read are often not exactly what the user typed on the command line.

选项

• number

  is a non-negative number indicating which argument of the current program command line is to be retrieved or queried.

  If number = 0, the argument pointed to is set to the name of the program (on systems that support this feature).

  if the processor does not have such a concept as a command name the value of command argument 0 is processor dependent.

  For values from 1 to the number of arguments passed to the program a value is returned in an order determined by the processor. Conventionally they are returned consecutively as they appear on the command line from left to right.

结果

• value

  The value argument holds the command line argument. If value can not hold the argument, it is truncated to fit the length of value.

  If there are less than number arguments specified at the command line or if the argument specified does not exist for other reasons, value will be filled with blanks.

• length

  The length argument contains the length of the n-th command line argument. The length of value has no effect on this value, It is the length required to hold all the significant characters of the argument regardless of how much storage is provided by value.

• status

  If the argument retrieval fails, status is a positive number; if value contains a truncated command line argument, status is -1; and otherwise the status is zero.

示例

示例程序：

program demo_get_command_argument
implicit none
character(len=255)           :: progname
integer                      :: count, i, argument_length, istat
character(len=:),allocatable :: arg

 ! command name assuming it is less than 255 characters in length
  call get_command_argument (0, progname, status=istat)
  if (istat == 0) then
     print *, "The program's name is " // trim (progname)
  else
     print *, "Could not get the program's name " // trim (progname)
  endif

 ! get number of arguments
  count = command_argument_count()
  write(*,*)'The number of arguments is ',count

  !
  ! allocate string array big enough to hold command line
  ! argument strings and related information
  !
  do i=1,count
     call get_command_argument(number=i,length=argument_length)
     if(allocated(arg))deallocate(arg)
     allocate(character(len=argument_length) :: arg)
     call get_command_argument(i, arg,status=istat)
     ! show the results
     write (*,'(i3.3,1x,i0.5,1x,i0.5,1x,"[",a,"]")') &
     & i,istat,argument_length,arg
  enddo

end program demo_get_command_argument

结果：

 ./demo_get_command_argument a  test 'of getting  arguments ' " leading"

 The program's name is ./demo_get_command_argument
 The number of arguments is            4
001 00000 00001 [a]
002 00000 00004 [test]
003 00000 00022 [of getting  arguments ]
004 00000 00008 [ leading]

标准

Fortran 2003

另见

get_command(3)，command_argument_count(3)

fortran-lang intrinsic descriptions (license: MIT) @urbanjost

cpu_time

名称

cpu_time(3) - [SYSTEM:TIME] Return CPU processor time used in seconds

Synopsis

     call cpu_time(time)

      subroutine cpu_time(time)

       real,intent(out) :: time

Characteristics

• time is a real of any kind

说明

cpu_time(3) returns a real value representing the elapsed CPU time in seconds. This is useful for testing segments of code to determine execution time.

If no time source is available, time is set to a negative value.

由于不同处理器能够提供的内容的可变性，时间的确切定义并不精确。

Note that time may contain a system dependent, arbitrary offset and may not start with 0.0. For cpu_time(3) the absolute value is meaningless. Only differences between subsequent calls, as shown in the example below, should be used.

PARALLEL PROCESSING

Whether the value assigned is an approximation to the amount of time used by the invoking image, or the amount of time used by the whole program, is processor dependent.

A processor for which a single result is inadequate (for example, a parallel processor) might choose to provide an additional version for which time is an array.

结果

• time

  is assigned a processor-dependent approximation to the processor time in seconds. If the processor cannot return a meaningful time, a processor-dependent negative value is returned.

  开始时间不精确，因为其目的是对代码段进行计时，如示例中所示。这可能包括也可能不包括系统开销时间。

示例

示例程序：

program demo_cpu_time
use, intrinsic :: iso_fortran_env, only : real_kinds,real32,real64,real128
implicit none
real :: start, finish
real(kind=real64) :: startd, finishd
   !
   call cpu_time(start)
   call cpu_time(startd)
   ! put code to time here
   call cpu_time(finish)
   call cpu_time(finishd)
   !
  ! writes processor time taken by the piece of code.

  ! the accuracy of the clock and whether it includes system time
  ! as well as user time is processor dependent. Accuracy up to
  ! milliseconds is common but not guaranteed, and may be much
  ! higher or lower
   print '("Processor Time = ",f6.3," seconds.")',finish-start

   ! see your specific compiler documentation for how to measure
   ! parallel jobs and for the precision of the time returned
   print '("Processor Time = ",g0," seconds.")',finish-start
   print '("Processor Time = ",g0," seconds.")',finishd-startd
end program demo_cpu_time

结果：

The precision of the result, some aspects of what is returned, and what if any options there are for parallel applications may very from system to system. See compiler-specific for details.

   Processor Time =  0.000 seconds.
   Processor Time = .4000030E-05 seconds.
   Processor Time = .2000000000000265E-05 seconds.

标准

Fortran 95

另见

system_clock(3)，date_and_time(3)

fortran-lang intrinsic descriptions (license: MIT) @urbanjost

date_and_time

名称

date_and_time(3) - [SYSTEM:TIME] Gets current date time

Synopsis

    call date_and_time( [date] [,time] [,zone] [,values] )

     subroutine date_and_time(date, time, zone, values)

      character(len=8),intent(out),optional :: date
      character(len=10),intent(out),optional :: time
      character(len=5),intent(out),optional :: zone
      integer,intent(out),optional :: values(8)

Characteristics

• *date is a default character scalar

• *time is a default character scalar

• *zone is a default character scalar

• values is a rank-one array of type integer with a decimal exponent range of at least four.

说明

date_and_time(3) gets the corresponding date and time information from the real-time system clock.

不可用的时间和日期_character_ 参数返回空白。

Unavailable numeric parameters return -huge(value).

These forms are compatible with the representations defined in ISO 8601:2004. UTC is established by the International Bureau of Weights and Measures (BIPM, i.e. Bureau International des Poids et Mesures) and the International Earth Rotation Service (IERS).

选项

• date

  A character string of default kind of the form CCYYMMDD, of length 8 or larger, where

  • CCYY is the year in the Gregorian calendar

  • MM is the month within the year

  • DD is the day within the month.

  The characters of this value are all decimal digits.

  If there is no date available, DATE is assigned all blanks.

• time

  A character string of default kind of the form HHMMSS.SSS, of length 10 or larger, where

  • hh is the hour of the day,

  • mm is the minutes of the hour,

  • and ss.sss is the seconds and milliseconds of the minute.

  Except for the decimal point, the characters of this value shall all be decimal digits.

  If there is no clock available, TIME is assigned all blanks.

• zone

  A string of the form (+-)HHMM, of length 5 or larger, representing the difference with respect to Coordinated Universal Time (UTC), where

  • hh and mm are the time difference with respect to Coordinated Universal Time (UTC) in hours and minutes, respectively.

  The characters of this value following the sign character are all decimal digits.

  If this information is not available, ZONE is assigned all blanks.

• values

  An array of at least eight elements. If there is no data available for a value it is set to -huge(values). Otherwise, it contains:

  • values(1) : The year, including the century.

  • values(2) : The month of the year

  • values(3)：一个月中的哪一天

  • values(4) : Time difference in minutes between the reported time and UTC time.

  • values(5) : The hour of the day, in the range 0 to 23.

  • values(6) : The minutes of the hour, in the range 0 to 59

  • values(7) : The seconds of the minute, in the range 0 to 60

  • values(8) : The milliseconds of the second, in the range 0 to 999.

The date, clock, and time zone information might be available on some images and not others. If the date, clock, or time zone information is available on more than one image, it is processor dependent whether or not those images share the same information.

示例

示例程序：

program demo_date_and_time
implicit none
character(len=8)     :: date
character(len=10)    :: time
character(len=5)     :: zone
integer,dimension(8) :: values

    call date_and_time(date,time,zone,values)

    ! using keyword arguments
    call date_and_time(DATE=date,TIME=time,ZONE=zone)
    print '(*(g0))','DATE="',date,'" TIME="',time,'" ZONE="',zone,'"'

    call date_and_time(VALUES=values)
    write(*,'(i5,a)') &
     & values(1),' - The year', &
     & values(2),' - The month', &
     & values(3),' - The day of the month', &
     & values(4),' - Time difference with UTC in minutes', &
     & values(5),' - The hour of the day', &
     & values(6),' - The minutes of the hour', &
     & values(7),' - The seconds of the minute', &
     & values(8),' - The milliseconds of the second'
end program demo_date_and_time

结果：

 > DATE="20201222" TIME="165738.779" ZONE="-0500"
 >  2020 - The year
 >    12 - The month
 >    22 - The day of the month
 >  -300 - Time difference with UTC in minutes
 >    16 - The hour of the day
 >    57 - The minutes of the hour
 >    38 - The seconds of the minute
 >   779 - The milliseconds of the second

标准

Fortran 95

另见

cpu_time(3)，system_clock(3)

Resources

日期和时间转换、格式化和计算

• M_time - https://github.com/urbanjost/M_time

• fortran-datetime https://github.com/dongli/fortran-datetime

• datetime-fortran - https://github.com/wavebitscientific/datetime-fortran

fortran-lang intrinsic descriptions (license: MIT) @urbanjost

system_clock

名称

system_clock(3) - [SYSTEM:TIME] Query system clock

Synopsis

    call system_clock([count] [,count_rate] [,count_max] )

     subroutine system_clock(count, count_rate, count_max)

      integer(kind=**),intent(out),optional   :: count
      type(TYPE(kind=**),intent(out),optional :: count_rate
      integer(kind=**),intent(out),optional   :: count_max

Characteristics

• count is an integer scalar

• count_rate is an integer or real scalar

• count_max is an integer scalar

说明

system_clock(3) lets you measure durations of time with the precision of the smallest time increment generally available on a system by returning processor-dependent values based on the current value of the processor clock.

system_clock 通常用于测量短时间间隔（例如，系统时钟可能是 24 小时制或测量自启动以来的处理器时钟节拍）。它最常用于测量或跟踪在代码块中花费的时间，而不是使用分析工具。

count_rate and count_max are assumed constant (even though CPU rates can vary on a single platform).

Whether an image has no clock, has a single clock of its own, or shares a clock with another image, is processor dependent.

如果没有时钟，或者查询时钟失败，count 设置为 -huge(count)，count_rate 和 count_max 设置为零。

The accuracy of the measurements may depend on the kind of the arguments!

Timing-related procedures are obviously processor and system-dependent. More specific information may generally be found in compiler-specific documentation.

选项

• count If there is no clock, the returned value for count is the negative value -huge(count).

  Otherwise, the clock value is incremented by one for each clock count until the value count_max is reached and is then reset to zero at the next count. clock therefore is a modulo value that lies in the range 0 to count_max.

• count_rate

  is assigned a processor-dependent approximation to the number of processor clock counts per second, or zero if there is no clock. count_rate is system dependent and can vary depending on the kind of the arguments. Generally, a large real may generate a more precise interval.

• count_max

  is assigned the maximum value that COUNT can have, or zero if there is no clock.

示例

如果处理器时钟是 24 小时制时钟，在上午 11:30 以大约每秒 18.20648193 个滴答的速度记录时间。参考资料

      call system_clock (count = c, count_rate = r, count_max = m)

定义

      C = (11*3600+30*60)*18.20648193 = 753748,
      R = 18.20648193, and
      M = 24*3600*18.20648193-1 = 1573039.

示例程序：

program demo_system_clock
use, intrinsic :: iso_fortran_env, only: wp => real64, int32, int64
implicit none
character(len=*), parameter :: g = '(1x,*(g0,1x))'

integer(kind=int64) :: count64, count_rate64, count_max64
integer(kind=int64) :: start64, finish64

integer(kind=int32) :: count32, count_rate32, count_max32
integer(kind=int32) :: start32, finish32

real(kind=wp)       :: time_read
real(kind=wp)       :: sum
integer             :: i

   print g, 'accuracy may vary with argument type!'

   print g, 'query all arguments'

   call system_clock(count64, count_rate64, count_max64)
   print g, 'COUNT_MAX(64bit)=', count_max64
   print g, 'COUNT_RATE(64bit)=', count_rate64
   print g, 'CURRENT COUNT(64bit)=', count64

   call system_clock(count32, count_rate32, count_max32)
   print g, 'COUNT_MAX(32bit)=', count_max32
   print g, 'COUNT_RATE(32bit)=', count_rate32
   print g, 'CURRENT COUNT(32bit)=', count32

   print g, 'time some computation'
   call system_clock(start64)

   ! some code to time
   sum = 0.0_wp
   do i = -0, huge(0) - 1
      sum = sum + sqrt(real(i))
   end do
   print g, 'SUM=', sum

   call system_clock(finish64)

   time_read = (finish64 - start64)/real(count_rate64, wp)
   write (*, '(1x,a,1x,g0,1x,a)') 'time : ', time_read, ' seconds'

end program demo_system_clock

结果：

 >  accuracy may vary with argument type!
 >  query all arguments
 >  COUNT_MAX(64bit)= 9223372036854775807
 >  COUNT_RATE(64bit)= 1000000000
 >  CURRENT COUNT(64bit)= 1105422387865806
 >  COUNT_MAX(32bit)= 2147483647
 >  COUNT_RATE(32bit)= 1000
 >  CURRENT COUNT(32bit)= 1105422387
 >  time some computation
 >  SUM= 66344288183024.266
 >  time :  6.1341038460000004  seconds

标准

Fortran 95

另见

date_and_time(3)，cpu_time(3)

fortran-lang intrinsic descriptions

execute_command_line

名称

execute_command_line(3) - [SYSTEM:PROCESSES] 执行一个shell命令

Synopsis

    call execute_command_line( &
    & command [,wait] [,exitstat] [,cmdstat] [,cmdmsg] )

     subroutine execute_command_line(command,wait,exitstat,cmdstat,cmdmsg)

      character(len=*),intent(in)             :: command
      logical,intent(in),optional             :: wait
      integer,intent(inout),optional          :: exitstat
      integer,intent(inout),optional          :: cmdstat
      character(len=*),intent(inout),optional :: cmdmsg

Characteristics

• command is a default character scalar

• wait is a default logical scalar. If wait is present with the

• exitstat is an integer of the default kind. It must be of a kind with at least a decimal exponent range of 9.

• cmdstat is an integer of default kind The kind of the variable must support at least a decimal exponent range of four.

• cmdmsg is a character scalar of the default kind.

说明

For execute_command_line(3) the command argument is passed to the shell and executed. (The shell is generally sh(1) on Unix systems, and cmd.exe on Windows.) If wait is present and has the value .false., the execution of the command is asynchronous if the system supports it; otherwise, the command is executed synchronously.

最后三个参数允许用户获取状态信息。同步执行后，exitstat 包含命令的整数退出代码，由 system 返回。如果执行了命令行（无论其退出状态是什么），cmdstat 将设置为零。如果发生错误，会为 cmdmsg 分配错误消息。

请注意，系统调用不必是线程安全的。如果需要，用户有责任确保不会同时调用系统。

当命令同步执行时，execute_command_line 在命令行完成执行后返回。否则，execute_command_line 无需等待即可返回。

因为这个内在函数是进行系统调用，所以它非常依赖于系统。它关于信令的行为取决于处理器。特别是，在 POSIX 兼容的系统上，SIGINT 和 SIGQUIT 信号将被忽略，而 SIGCHLD 将被阻止。因此，如果父进程终止，子进程可能不会同时终止。

选项

• command

  the command line to be executed. The interpretation is programming-environment dependent.

• 等待

  If wait is present with the value .false., and the processor supports asynchronous execution of the command, the command is executed asynchronously; otherwise it is executed synchronously.

  When the command is executed synchronously, execute_command_line(3) returns after the command line has completed execution. Otherwise, execute_command_line(3) returns without waiting.

• exitstat

  If the command is executed synchronously, it is assigned the value of the processor-dependent exit status. Otherwise, the value of exitstat is unchanged.

• cmdstat

  If an error condition occurs and cmdstat is not present, error termination of execution of the image is initiated.

  如果处理器不支持命令行执行，则分配值 -1，如果发生错误条件，则分配与处理器相关的正值，或者如果没有错误条件发生，则分配值 -2 但** wait** 存在值 false 并且处理器不支持异步执行。否则，它被赋值为 0。

• cmdmsg

  If an error condition occurs, it is assigned a processor-dependent explanatory message. Otherwise, it is unchanged.

示例

示例程序：

program demo_exec
implicit none
   integer :: i

   call execute_command_line("external_prog.exe", exitstat=i)
   print *, "Exit status of external_prog.exe was ", i

   call execute_command_line("reindex_files.exe", wait=.false.)
   print *, "Now reindexing files in the background"
end program demo_exec

标准

Fortran 2008

See also

get_environment_variable(3)

fortran-lang intrinsic descriptions (license: MIT) @urbanjost

get_environment_variable

名称

get_environment_variable(3) - [SYSTEM:ENVIRONMENT] Get value of an environment variable

Synopsis

    call get_environment_variable(name [,value] [,length] &
    & [,status] [,trim_name] [,errmsg] )

     subroutine character(len=*) get_environment_variable( &
     & name, value, length, status, trim_name, errmsg )

      character(len=*),intent(in) :: name
      character(len=*),intent(out),optional   :: value
      integer(kind=**),intent(out),optional   :: length
      integer(kind=**),intent(out),optional   :: status
      logical,intent(out),optional            :: trim_name
      character(len=*),intent(inout),optional :: errmsg

Characteristics

• a kind designated as ** may be any supported kind for the type meeting the conditions described herein.

• name, value, and errmsg are a scalar character of default kind.

• length and status are integer scalars with a decimal exponent range of at least four.

• trim_name is a scalar of type logical and of default kind.

说明

get_environment_variable(3) gets the value of the environment variable name.

请注意，get_environment_variable(3) 不必是线程安全的。用户有责任确保环境不会同时更新。

If running in parallel be aware It is processor dependent whether an environment variable that exists on an image also exists on another image, and if it does exist on both images whether the values are the same or different.

选项

• name

  The name of the environment variable to query. The interpretation of case is processor dependent.

结果

• value

  The value of the environment variable being queried. If value is not large enough to hold the data, it is truncated. If the variable name is not set or has no value, or the processor does not support environment variables value will be filled with blanks.

• length

  Argument length contains the length needed for storing the environment variable name. It is zero if the environment variable is not set.

• status

  status 是 -1 如果 value 存在但对于环境变量来说太短了；如果环境变量不存在，则为 1，如果处理器不支持环境变量，则为 2；在所有其它情况下，status 为零。

• trim_name

  If trim_name is present with the value .false., the trailing blanks in name are significant; otherwise they are not part of the environment variable name.

示例

示例程序：

program demo_getenv
implicit none
character(len=:),allocatable :: homedir
character(len=:),allocatable :: var

     var='HOME'
     homedir=get_env(var)
     write (*,'(a,"=""",a,"""")')var,homedir

contains

function get_env(name,default) result(value)
! a function that makes calling get_environment_variable(3) simple
implicit none
character(len=*),intent(in)          :: name
character(len=*),intent(in),optional :: default
character(len=:),allocatable         :: value
integer                              :: howbig
integer                              :: stat
integer                              :: length
   length=0
   value=''
   if(name.ne.'')then
      call get_environment_variable( name, &
      & length=howbig,status=stat,trim_name=.true.)
      select case (stat)
      case (1)
       print *, name, " is not defined in the environment. Strange..."
       value=''
      case (2)
       print *, &
       "This processor does not support environment variables. Boooh!"
       value=''
      case default
       ! make string of sufficient size to hold value
       if(allocated(value))deallocate(value)
       allocate(character(len=max(howbig,1)) :: value)
       ! get value
       call get_environment_variable( &
       & name,value,status=stat,trim_name=.true.)
       if(stat.ne.0)value=''
      end select
   endif
   if(value.eq.''.and.present(default))value=default
end function get_env

end program demo_getenv

典型结果：

   HOME="/home/urbanjs"

标准

Fortran 2003

See also

get_command_argument(3), get_command(3)

fortran-lang intrinsic descriptions (license: MIT) @urbanjost