freepascal.compiler/docs/dos.xml

<?xml version="1.0" encoding="ISO8859-1"?>
<fpdoc-descriptions>
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<package name="rtl">
<module name="DOS">
<short>DOS - Turbo Pascal MS-DOS interface</short>
<!-- \FPCexampledir{dosex} -->
<descr>
<p>
The <file>DOS</file> unit gives access to some operating system calls 
related to files, the file system, date and time. Except for the 
PalmOS target, this unit is available to all supported platforms.
</p>
<p>
The unit was first written for dos by Florian Klaempfl. It was ported to 
linux by Mark May and enhanced by Michael Van Canneyt. 
The Amiga version was ported by Nils Sjoholm.
</p>
<p>
Under non-DOS systems, some of the functionality is lost, as it is either impossible 
or meaningless to implement it. Other than that, the functionality for all 
operating systems is the same.
</p>
</descr>

<topic name="fileattributes">
<short>File attributes</short>
<descr>
<p>
The File Attribute constants are used in <link id="FindFirst"/>,
<link id="FindNext"/> to
determine what type of special file to search for in addition to normal files. 
These flags are also used in the <link id="SetFAttr"/> and <link id="GetFAttr"/> routines to 
set and retrieve attributes of files. For their definitions consult 
<link id="fileattributes"/>.
</p>
<table>
<caption>Possible file attributes</caption>
<th><td>Constant</td><td>Description</td><td>Value</td></th>
<tr><td><var>readonly</var></td><td><printshort id="readonly"/></td><td> $01</td></tr>
<tr><td><var>hidden</var> </td><td> <printshort id="hidden"/> </td><td> $02 </td></tr>
<tr><td><var>sysfile</var> </td><td> <printshort id="sysfile"/> </td><td> $04</td></tr>
<tr><td><var>volumeid</var> </td><td>  <printshort id="volumeid"/> </td><td> $08</td></tr>
<tr><td><var>directory</var> </td><td> <printshort id="directory"/> </td><td> $10</td></tr>
<tr><td><var>archive</var> </td><td> <printshort id="archive"/> </td><td> $20</td></tr> 
<tr><td><var>anyfile</var> </td><td> <printshort id="anyfile"/> </td><td> $3F</td></tr>
</table>
</descr>
</topic>

<topic name="filemodes">
<short>File open mode constants.</short>
<descr>
<p>
These constants are used in the <var>Mode</var> field of the <var>TextRec</var>
record. Gives information on the filemode of the text I/O. For their
definitions consult the following table:
</p>
<table>
<caption>Possible mode constants</caption>
<th><td>Constant</td><td>Description</td><td>Value</td></th> 
<tr><td><var>fmclosed</var></td><td><printshort id="fmclosed"/></td><td>$D7B0</td></tr>
<tr><td><var>fminput</var></td><td><printshort id="fminput"/></td><td>$D7B1 </td></tr>
<tr><td><var>fmoutput</var></td><td><printshort id="fmoutput"/></td><td>$D7B2</td></tr>
<tr><td><var>fminout</var></td><td><printshort id="fminout"/></td><td>$D7B3</td></tr>
</table>
</descr>
</topic>

<topic name="filehandling">
<short>File handling</short>
<descr>
<p>
Routines to handle files on disk.
</p>
<table>
<th><td>Name</td><td>Description</td></th>
<tr><td><link id="FExpand"/></td><td>Expand filename to full path</td></tr>
<tr><td><link id="FindClose"/></td><td>Close finfirst/findnext session</td></tr>
<tr><td><link id="FindFirst"/></td><td>Start find of file</td></tr>
<tr><td><link id="FindNext"/></td><td>Find next file</td></tr>
<tr><td><link id="FSearch"/></td><td>Search for file in a path</td></tr>
<tr><td><link id="FSplit"/></td><td>Split filename in parts</td></tr>
<tr><td><link id="GetFAttr"/></td><td>Return file attributes</td></tr>
<tr><td><link id="GetFTime"/></td><td>Return file time</td></tr>
<tr><td><link id="GetLongName"/></td><td>Convert short filename to long filename (DOS only)</td></tr>
<tr><td><link id="GetShortName"/></td><td>Convert long filename to short filename (DOS only)</td></tr>
<tr><td><link id="SetFAttr"/></td><td>Set file attributes</td></tr>
<tr><td><link id="SetFTime"/></td><td>Set file time</td></tr>
</table>
</descr>
</topic>

<topic name="diskhandling">
<short>Directory and disk handling</short>
<descr>
<p>
Routines to handle disk information.
</p>
<table>
<th><td>Name</td><td>Description</td></th>
<tr><td><link id="AddDisk"/></td><td>Add disk to list of disks (UNIX only)</td></tr>
<tr><td><link id="DiskFree"/></td><td>Return size of free disk space</td></tr>
<tr><td><link id="DiskSize"/></td><td>Return total disk size</td></tr>
</table>
</descr>
</topic>

<topic name="process">
<short>Process handling</short>
<descr>
<p>
Functions to handle process information and starting new processes.
</p>
<table>
<th><td>Name</td><td>Description</td></th>
<tr><td><link id="DosExitCode"/></td><td>Exit code of last executed program</td></tr>
<tr><td><link id="EnvCount"/></td><td>Return number of environment variables</td></tr>
<tr><td><link id="EnvStr"/></td><td>Return environment string pair</td></tr>
<tr><td><link id="Exec"/></td><td>Execute program</td></tr>
<tr><td><link id="GetEnv"/></td><td>Return specified environment string</td></tr>
</table>
</descr>
</topic>

<topic name="sysinfo">
<short>System information</short>
<descr>
<p>
Functions for retrieving and setting general system information such as date
and time.
</p>
<table>
<th><td>Name</td><td>Description</td></th>
<tr><td><link id="DosVersion"/></td><td>Get OS version</td></tr>
<tr><td><link id="GetCBreak"/></td><td>Get setting of control-break handling flag</td></tr>
<tr><td><link id="GetDate"/></td><td>Get system date</td></tr>
<tr><td><link id="GetIntVec"/></td><td>Get interrupt vector status</td></tr>
<tr><td><link id="GetTime"/></td><td>Get system time</td></tr>
<tr><td><link id="GetVerify"/></td><td>Get verify flag</td></tr>
<tr><td><link id="Intr"/></td><td>Execute an interrupt</td></tr>
<tr><td><link id="Keep"/></td><td>Keep process in memory and exit</td></tr>
<tr><td><link id="MSDos"/></td><td>Execute MS-dos function call</td></tr>
<tr><td><link id="PackTime"/></td><td>Pack time for file time</td></tr>
<tr><td><link id="SetCBreak"/></td><td>Set control-break handling flag</td></tr>
<tr><td><link id="SetDate"/></td><td>Set system date</td></tr>
<tr><td><link id="SetIntVec"/></td><td>Set interrupt vectors</td></tr>
<tr><td><link id="SetTime"/></td><td>Set system time</td></tr>
<tr><td><link id="SetVerify"/></td><td>Set verify flag</td></tr>
<tr><td><link id="SwapVectors"/></td><td>Swap interrupt vectors</td></tr>
<tr><td><link id="UnPackTime"/></td><td>Unpack file time</td></tr>
</table>
</descr>
</topic>


<element name="fmclosed">
<short>File is closed</short>
</element>

<element name="fminput">
<short>File is read only</short>
</element>

<element name="fmoutput">
<short>File is write only</short>
</element>

<element name="fminout">
<short>File is read and write</short>
</element>

<element name="fcarry">
<short>CPU carry flag. Not used.</short>
</element>

<element name="fparity">
<short>CPU parity flag. Not used.</short>
</element>

<element name="fauxiliary">
<short>CPU auxiliary flag. Not used.</short>
</element>

<element name="fzero">
<short>CPU zero flag. Not used.</short>
</element>

<element name="fsign">
<short>CPU sign flag. Not used.</short>
</element>

<element name="foverflow">
<short>CPU overflow flag. Not used.</short>
</element>

<element name="readonly">
<short>Read-Only file attribute</short>
</element>

<element name="hidden">
<short>Hidden file attribute</short>
</element>

<element name="sysfile">
<short>System file attribute</short>
</element>

<element name="volumeid">
<short>Volumd ID file attribute</short>
</element>

<element name="directory">
<short>Directory file attribute</short>
</element>

<element name="archive">
<short>Archive file attribute</short>
</element>

<element name="FileNameLen">
<short>Maximum length of a filename</short>
</element>

<element name="anyfile">
<short>Match any file attribute</short>
</element>

<element name="ComStr">
<short>Command-line string type</short>  
</element>

<element name="PathStr">
<short>Full File path string type.</short>  
</element>

<element name="DirStr">
<short>Full directory string type.</short>  
</element>

<element name="NameStr">
<short>Fill filename string type.</short>  
</element>

<element name="ExtStr">
<short>Filename extension string type.</short>  
</element>

<element name="SearchRec">
<short>File Search Results record</short>
<descr>
<p>
<var>SearchRec</var> is filled by the <link id="FindFirst"/> call and can be
used in subsequent <link id="FindNext"/> calls to search for files. The
structure of this record depends on the platform. Only the following
fields are present on all platforms: 
</p>
<dl>
<dt>Attr</dt><dd>File attributes.</dd>
<dt>Time</dt><dd>File modification time.</dd>
<dt>Size</dt><dd>File size</dd>
<dt>Name</dt><dd>File name (name part only, no path)</dd>
</dl>
</descr>
</element>

<element name="filerecnamelength">
<short>Maximum length of FileName part in <link id="FileRec"/></short>
</element>

<element name="FileRec">
<short>Record describing an untyped file</short>
<descr>
<var>FileRec</var> is used for internal representation of typed and untyped files.
</descr>
</element>

<element name="FileRec.Handle">
<short>OS file handle</short>
</element>

<element name="FileRec.Mode">
<short>File open mode</short>
</element>

<element name="FileRec.RecSize">
<short>Size of a record (in bytes)</short>
</element>

<element name="FileRec._Private">
<short>Private data, do not use</short>
</element>

<element name="FileRec.UserData">
<short>User data, for implementing a user driver.</short>
</element>

<element name="FileRec.Name">
<short>File name</short>
</element>

<element name="TextRecNameLength">
<short>Maximum length of filename in <link id="TextRec"/></short>
</element>

<element name="TextRecBufSize">
<short>Size of default buffer in <link id="TextRec"/></short>
</element>

<element name="TextBuf">
<short>Type for default buffer in <link id="TextRec"/></short>
</element>

<element name="TextRec">
<short>Record describing Text files</short>
<descr>
<p>
<var>TextRec</var> describes the internal working of a <var>Text</var> file.
</p>
<p>
Remark that this is not binary compatible with the Turbo Pascal definition
of <var>TextRec</var>, since the sizes of the different fields are different.
</p>
</descr>
</element>

<element name="Handle">
<short>OS file handle for this record</short>
</element>

<element name="Mode">
<short>File open mode</short>
</element>

<element name="bufsize">
<short>Current buffer size.</short>
</element>

<element name="bufpos">
<short>Current buffer position.</short>
</element>

<element name="bufend">
<short>Current length of data in buffer</short>
</element>

<element name="bufptr">
<short>Pointer tuo buffer.</short>
</element>

<element name="openfunc">
<short>Called when file needs to be opened.</short>
</element>

<element name="inoutfunc">
<short>Called when an I/O operation needs to be performed.</short>
</element>

<element name="flushfunc">
<short>Called when buffer must be flushed.</short>
</element>

<element name="closefunc">
<short>Called when file must be closed.</short>
</element>

<element name="UserData">
<short>Room for user data when implementing custom text file.</short>
</element>

<element name="name">
<short>File name.</short>
</element>

<element name="buffer">
<short>Default buffer.</short>
</element>

<element name="Registers">
<short>Record to keep CPU registers for <link id="MSDos"/> call. Unused.</short>
</element>
<element name="DateTime">
<short>Record containing a date/time description</short>
<descr>
The <var>DateTime</var> type is used in <link id="PackTime"/> and <link id="UnPackTime"/> for
setting/reading file times with <link id="GetFTime"/> and <link id="SetFTime"/>.
</descr>
</element>

<element name="DateTime.Year">
<short>Year part</short>
</element>
<element name="DateTime.Month">
<short>Month of the year</short>
</element>
<element name="DateTime.Day">
<short>Day of the month</short>
</element>
<element name="DateTime.Hour">
<short>Hour of the day</short>
</element>
<element name="DateTime.Min">
<short>Minute of the hour</short>
</element>
<element name="DateTime.Sec">
<short>Second in the minute</short>
</element>

<element name="DosError">
<short>Last OS (MS-DOS) error</short>
<descr>
<p>
The <var>DosError</var> variable is used by the procedures in the dos unit to 
report errors. It can have the following values :
</p>
<table>
<caption>Dos error codes</caption>
<th><td>Value</td><td>Meaning</td></th>
<tr><td>2 </td><td> File not found. </td></tr>
<tr><td>3 </td><td> path not found. </td></tr>
<tr><td>5 </td><td> Access denied. </td></tr>
<tr><td>6 </td><td> Invalid handle. </td></tr>
<tr><td>8 </td><td> Not enough memory. </td></tr>
<tr><td>10 </td><td> Invalid environment. </td></tr>
<tr><td>11 </td><td> Invalid format. </td></tr>
<tr><td>18 </td><td> No more files.</td></tr>
</table>
<p>
Other values are possible, but are not documented.
</p>
</descr>
</element>

<element name="drivestr">
<short>Pathnames representing drives.</short>
<descr>
This variable is defined in the linux version of the dos unit. It is used
in the <link id="DiskFree"/> and <link id="DiskSize"/> calls.
</descr>
</element>

<element name="AddDisk">
<short>Add disk definition to list if drives (Unix only)</short>
<descr>
<p>
<var>AddDisk</var> adds a filename <var>S</var> to the internal list of disks. It is
implemented for systems which do not use DOS type drive letters.
 This list is used to determine which disks to use in the <link id="DiskFree"/>
and <link id="DiskSize"/> calls. 
The <link id="DiskFree"/> and <link id="DiskSize"/> functions need a file on the 
specified drive, since this is required for the <var>statfs</var> system call.
The names are added sequentially. The dos
initialization code presets the first three disks to:
</p>
<ul>
<li> <var>'.'</var> for the current drive, </li>
<li> <var>'/fd0/.'</var> for the first floppy-drive (linux only).</li>
<li> <var>'/fd1/.'</var> for the second floppy-drive (linux only).</li>
<li> <var>'/'</var> for the first hard disk.</li>
</ul>
<p>
The first call to <var>AddDisk</var> will therefore add a name for the second
harddisk, The second call for the third drive, and so on until 23 drives
have been added (corresponding to drives <var>'D:'</var> to <var>'Z:'</var>)
</p>
</descr>
<errors>
None
</errors>
<seealso>
<link id="DiskFree"/>
<link id="DiskSize"/> 
</seealso>
</element>


<element name="DiskFree">
<short>Get free size on Disk.</short>
<descr>
<p>
<var>DiskFree</var> returns the number of free bytes on a disk. The parameter
<var>Drive</var> indicates which disk should be checked. This parameter is 1 for
floppy <var>a:</var>, 2 for floppy <var>b:</var>, etc. A value of 0 returns the free
space on the current drive. 
</p>
<remark>
For Unices:
The <var>diskfree</var> and <var>disksize</var> functions need a file on the 
specified drive, since this is required for the <var>statfs</var> system call.
These filenames are set in the initialization of the dos unit, and have 
been preset to :
</remark>
<ul>
<li> <var>'.'</var> for the current drive, </li>
<li> <var>'/fd0/.'</var> for the first floppy-drive (linux only).</li>
<li> <var>'/fd1/.'</var> for the second floppy-drive (linux only).</li>
<li> <var>'/'</var> for the first hard disk.</li>
</ul>
<p>
There is room for 1-26 drives. You can add a drive with the
<link id="AddDisk"/> procedure.
These settings can be coded in <var>dos.pp</var>, in the initialization part.
</p>
</descr>
<errors>
-1 when a failure occurs, or an invalid drive number is given.
</errors>
<seealso>
<link id="DiskSize"/>
<link id="AddDisk"/>
</seealso>
<example file="dosex/ex6"/>
</element>


<element name="DiskSize">
<short>Get total size of disk.</short>
<descr>
<p>
<var>DiskSize</var> returns the total size (in bytes) of a disk. The parameter
<var>Drive</var> indicates which disk should be checked. This parameter is 1 for
floppy <var>a:</var>, 2 for floppy <var>b:</var>, etc. A value of 0 returns the size
of the current drive. 
</p>
<remark>
For unix only:
The <var>diskfree</var> and <var>disksize</var> functions need a file on the specified drive, since this
is required for the <var>statfs</var> system call.
These filenames are set in the initialization of the dos unit, and have 
been preset to :
</remark>
<ul>
<li> <var>'.'</var> for the current drive, </li>
<li> <var>'/fd0/.'</var> for the first floppy-drive (linux only).</li>
<li> <var>'/fd1/.'</var> for the second floppy-drive (linux only).</li>
<li> <var>'/'</var> for the first hard disk.</li>
</ul>
<p>
There is room for 1-26 drives. You can add a drive with the
<link id="AddDisk"/> procedure.
These settings can be coded in <var>dos.pp</var>, in the initialization part.
</p>
<p>
For an example, see <link id="DiskFree"/>.
</p>
</descr>
<errors>
-1 when a failure occurs, or an invalid drive number is given.
</errors>
<seealso>
<link id="DiskFree"/>
<link id="AddDisk"/>
</seealso>
</element>

<element name="DosExitCode">
<short>Exit code of last executed program.</short>
<descr>
<var>DosExitCode</var> contains (in the low byte) the exit-code of a program 
executed with the <var>Exec</var> call.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="Exec"/>
</seealso>
<example file="dosex/ex5"/>
</element>

<element name="DosVersion">
<short>Current OS version</short>
<descr>
<p>
<var>DosVersion</var> returns the operating system or kernel version. The
low byte contains the major version number, while the high byte 
contains the minor version number.
</p>
<remark>
On systems where versions consists of more then two numbers, 
only the first two numbers will be returned. For example Linux version 2.1.76 
will give you DosVersion 2.1. Some operating systems, such as FreeBSD, do not
have system calls to return the kernel version, in that case a value of 0 will
be returned.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
</seealso>
<example file="dosex/ex1"/>
</element>

<element name="EnvCount">
<short>Return the number of environment variables</short>
<descr>
<var>EnvCount</var> returns the number of environment variables.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="EnvStr"/>
<link id="GetEnv"/>
</seealso>
</element>

<element name="EnvStr">
<short>Return environment variable by index</short>
<descr>

<var>EnvStr</var> returns the <var>Index</var>-th <var>Name=Value</var> pair from the list
of environment variables. 
The index of the first pair is zero.
</descr>
<errors>
The length is limited to 255 characters. 
</errors>
<seealso>
<link id="EnvCount"/>
<link id="GetEnv"/>
</seealso>
<example file="dosex/ex13"/>
</element>


<element name="Exec">
<short>Execute another program, and wait for it to finish.</short>
<descr>
<p>
<var>Exec</var> executes the program in <var>Path</var>, with the options given by
<var>ComLine</var>.
</p>
<p>
After the program has terminated, the procedure returns. The Exit value of
the program can be consulted with the <var>DosExitCode</var> function.
</p>
<p>
For an example, see <link id="DosExitCode"/>
</p>
</descr>
<errors>
Errors are reported in <var>DosError</var>.
</errors>
<seealso>
<link id="DosExitCode"/>
</seealso>
</element>

<element name="FExpand">
<short>Expand a relative path to an absolute path</short>
<descr>
<p>
<var>FExpand</var> takes its argument and expands it to a complete filename, i.e.
a filename starting from the root directory of the current drive, prepended
with the drive-letter or volume name (when supported).
</p>
<remark>
On case sensitive file systems (such as unix and linux), the resulting
name is left as it is, otherwise it is converted to uppercase.
</remark>
</descr>
<errors>
<link id="FSplit"/>
</errors>
<seealso>
</seealso>
<example file="dosex/ex5"/>
</element>


<element name="FindClose">
<short>Dispose resources allocated by a <link id="FindFirst"/>/<link
id="FindNext"/> sequence.</short>
<descr>
<p>
<var>FindClose</var> frees any resources associated with the search record
<var>F</var>.
</p>
<p>
This call is needed to free any internal resources allocated by the 
<link id="FindFirst"/> or <link id="FindNext"/> calls.
</p>
<p>
The unix implementation of the dos unit therefore keeps a table of open
directories, and when the table is full, closes one of the directories, and
reopens another. This system is adequate but slow if you use a lot of
<var>searchrecs</var>.
</p>
<p>
So, to speed up the findfirst/findnext system, the <var>FindClose</var> call was
implemented. When you don't need a <var>searchrec</var> any more, you can tell
this to the dos unit by issuing a <var>FindClose</var> call. The directory
which is kept open for this <var>searchrec</var> is then closed, and the table slot
freed.
</p>
<remark>
It is recommended to use the linux call <var>Glob</var> when looking for files 
on linux.
</remark>
</descr>
<errors>
Errors are reported in DosError.
</errors>
<seealso>
<link id="FindFirst"/>
<link id="FindNext"/>
</seealso>
</element>

<element name="FindFirst">
<short>Start search for one or more files.</short>
<descr>
<p>
<var>FindFirst</var> searches the file specified in <var>Path</var>. Normal files,
as well as all special files which have the attributes specified in
<var>Attr</var> will be returned.
</p>
<p>
It returns a <var>SearchRec</var> record for further searching in <var>F</var>.
<var>Path</var> can contain the wildcard characters <var>?</var> (matches any single
character) and <var>*</var> (matches 0 ore more arbitrary characters). In this
case <var>FindFirst</var> will return the first file which matches the specified
criteria.
If <var>DosError</var> is different from zero, no file(s) matching the criteria 
was(were) found.
</p>
<remark>
On os/2, you cannot issue two different <var>FindFirst</var> calls. That is,
you must close any previous search operation with <link id="FindClose"/> before
starting a new one. Failure to do so will end in a Run-Time Error 6 
(Invalid file handle)
</remark>
</descr>
<errors>
Errors are reported in DosError.
</errors>
<seealso>
<link id="FindNext"/>,
<link id="FindClose"/>
</seealso>
<example file="dosex/ex7"/>
</element>


<element name="FindNext">
<short>Find next matching file after <link id="FindFirst"/></short>
<descr>
<p>
<var>FindNext</var> takes as an argument a <var>SearchRec</var> from a previous
<var>FindNext</var> call, or a <var>FindFirst</var> call, and tries to find another
file which matches the criteria, specified in the <var>FindFirst</var> call.
If <var>DosError</var> is different from zero, no more files matching the
criteria were found.
</p>
<p>
For an example, see <link id="FindFirst"/>.
</p>
</descr>
<errors>
<var>DosError</var> is used to report errors.
</errors>
<seealso>
<link id="FindFirst"/>
<link id="FindClose"/>
</seealso>
</element>

<element name="FSearch">
<short>Search a file in searchpath</short>
<descr>
<p>
<var>FSearch</var> searches the file <var>Path</var> in all directories listed in
<var>DirList</var>. The full name of the found file is returned.
<var>DirList</var> must be a list of directories, separated by semi-colons.
When no file is found, an empty string is returned.
</p>
<remark>
On unix systems, <var>DirList</var> can also be separated by colons, as is
customary on those environments.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="FExpand">FExpand</link>
</seealso>
<example file="dosex/ex10"/>
</element>


 
<element name="FSplit">
<short>Split a full-path filename in parts.</short>
<descr>
<var>FSplit</var> splits a full file name into 3 parts : A <var>Path</var>, a
<var>Name</var> and an extension  (in <var>ext</var>.) 
The extension is taken to be all letters after the <em> last</em> dot (.). For 
dos, however, an exception is made when <var>LFNSupport=False</var>, then
the extension is defined as all characters after the <em> first</em> dot.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="FSearch">FSearch</link>
</seealso>
<example file="dosex/ex12"/>
</element>


<element name="GetCBreak">
<short>Get control-Break flag</short>
<descr>
<p>
<var>GetCBreak</var> gets the status of CTRL-Break checking under dos and Amiga.
When <var>BreakValue</var> is <var>false</var>, then dos only checks for the 
CTRL-Break key-press when I/O is performed. When it is set to <var>True</var>,
then a check is done at every system call.
</p>
<remark>
Under non-dos and non-Amiga operating systems, <var>BreakValue</var> always returns 
<var>True</var>.
</remark>
</descr>
<errors> 
None
</errors>
<seealso>
<link id="SetCBreak"/>
</seealso>
</element>

<element name="GetDate">
<short>Get the current date</short>
<descr>
<var>GetDate</var> returns the system's date. <var>Year</var> is a number in the range
1980..2099.<var>mday</var> is the day of the month,
<var>wday</var> is the day of the week, starting with Sunday as day 0.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetTime"/>
<link id="SetDate"/>
</seealso>
<example file="dosex/ex2"/>
</element>


<element name="GetEnv">
<short>Get environment variable by name.</short>
<descr>
<p>
<var>Getenv</var> returns the value of the environment variable <var>EnvVar</var>.
When there is no environment variable <var>EnvVar</var> defined, an empty
string is returned.
</p>
<remark>
Under some operating systems (such as unix), case is important when looking
for <var>EnvVar</var>.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="EnvCount"/>
<link id="EnvStr"/>
</seealso>
<example file="dosex/ex14"/>
</element>

<element name="GetFAttr">
<short>Get file attributes</short>
<descr>
<p>
<var>GetFAttr</var> returns the file attributes of the file-variable <var>f</var>.
 <var>F</var> can be a untyped or typed file, or of type <var>Text</var>. <var>f</var> must
have been assigned, but not opened. The attributes can be examined with the
following constants :
</p>
<ul>
<li> <var>ReadOnly</var></li>
<li> <var>Hidden</var></li>
<li> <var>SysFile</var></li>
<li> <var>VolumeId</var></li>
<li> <var>Directory</var></li>
<li> <var>Archive</var></li>
</ul>
<p>
Under linux, supported attributes are:
</p>
<ul>
<li> <var>Directory</var></li>
<li> <var>ReadOnly</var> if the current process doesn't have access to the file.</li>
<li> <var>Hidden</var> for files whose name starts with a dot <var>('.')</var>.</li>
</ul>
</descr>
<errors>
Errors are reported in <var>DosError</var>
</errors>
<seealso>
<link id="SetFAttr"/>
</seealso>
<example file="dosex/ex8"/>
</element>


<element name="GetFTime">
<short>Get file last modification time.</short>
<descr>
<var>GetFTime</var> returns the modification time of a file.
This time is encoded and must be decoded with <var>UnPackTime</var>. 
<var>F</var> must be a file type, which has been assigned, and
opened.
</descr>
<errors>
Errors are reported in <var>DosError</var>
</errors>
<seealso>
<link id="SetFTime"/>
<link id="PackTime"/>
<link id="UnPackTime"/>
</seealso>
<example file="dosex/ex9"/>
</element>


<element name="GetIntVec">
<short>Get interrupt vector</short>
<descr>
<p>
<var>GetIntVec</var> returns the address of interrupt vector
<var>IntNo</var>.
</p>
<remark>
This call does nothing, it is present for compatibility only. Modern systems
do not allow low level access to the hardware.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="SetIntVec"/>
</seealso>
</element>

<element name="GetLongName">
<short>Get the long filename of a DOS 8.3 filename.</short>
<descr>
<p>
This function is only implemented in the GO32V2 version of Free Pascal.
</p>
<p>
<var>GetLongName</var> changes the filename <var>p</var> to a long filename
if the dos call to do this is successful. The resulting string
is the long  file name corresponding to the short filename <var>p</var>.
</p>
<p>
The function returns <var>True</var> if the dos call was successful, 
<var>False</var> otherwise.
</p>
<p>
This function should only be necessary when using the DOS extender
under Windows 95 and higher.
</p>
</descr>
<errors>
If the dos call was not succesfull, <var>False</var> is returned.
</errors>
<seealso>
<link id="GetShortName"/>
</seealso>
</element>

<element name="GetShortName">
<short>Get the short (8.3) filename of a long filename.</short>
<descr>
<p>
This function is only implemented in the GO32V2 version of Free Pascal.
</p>
<p>
<var>GetShortName</var> changes the filename <var>p</var> to a short filename
if the dos call to do this is successful. The resulting string
is the short file name corresponding to the long filename <var>p</var>.
</p>
<p>
The function returns <var>True</var> if the dos call was successful, 
<var>False</var> otherwise.
</p>
<p>
This function should only be necessary when using the DOS extender
under Windows 95 and higher.
</p>
</descr>
<errors>
If the dos call was not successful, <var>False</var> is returned.
</errors>
<seealso>
<link id="GetLongName"/>
</seealso>
</element>

<element name="GetTime">
<short>Return the current time</short>
<descr>
<p>
<var>GetTime</var> returns the system's time. <var>Hour</var> is a on a 24-hour time
scale. <var>sec100</var> is in hundredth of a
second.
</p>
<remark>
Certain operating systems (such as Amiga), always set the <var>sec100</var> field
to zero.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetDate"/>
<link id="SetTime"/>
</seealso>
<example file="dosex/ex3"/>
</element>


<element name="GetVerify">
<short>Get verify flag</short>
<descr>
<p>
<var>GetVerify</var> returns the status of the verify flag under dos. When
<var>Verify</var> is <var>True</var>, then dos checks data which are written to disk,
by reading them after writing. If <var>Verify</var> is <var>False</var>, then data
written to disk are not verified.
</p>
<remark>
Under non-dos systems (excluding os/2 applications running under vanilla DOS),  
Verify is always <var>True</var>.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="SetVerify"/>
</seealso>
</element>

<element name="Intr">
<short>Execute interrupt</short>
<descr>
<p>
<var>Intr</var> executes a software interrupt number <var>IntNo</var> (must be between
0 and 255), with processor registers set to <var>Regs</var>. After the interrupt call
returned, the processor registers are saved in <var>Regs</var>.
</p>
<remark>
Under non-dos operating systems, this call does nothing.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="MSDos"/>
</seealso>
</element>

<element name="Keep">
<short>Terminate and stay resident.</short>
<descr>
<p>
<var>Keep</var> terminates the program, but stays in memory. This is used for TSR
(Terminate Stay Resident) programs which catch some interrupt.
<var>ExitCode</var> is the same parameter as the <var>Halt</var> function takes.
</p>
<remark>
This call does nothing, it is present for compatibility only.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
</seealso>
</element>

<element name="weekday">
<short>Return the day of the week</short>
<descr>
<var>WeekDay</var> returns the day of the week on which the day
<var>Y/M/D</var> falls. Sunday is represented by 0, Saturday is 6.
</descr>
<errors>
On error, -1 is returned.
</errors>
<seealso>
<link id="PackTime"/>
<link id="UnpackTime"/>
<link id="GetTime"/>
<link id="SetTime"/>
</seealso>
</element>

<element name="DTToUnixDate">
<short>Convert a DateTime to unix timestamp</short>
<descr>
<var>DTToUnixDate</var> converts the DateTime value in <var>DT</var> to a
unix timestamp. It is an internal function, implemented on Unix platforms,
and should not be used.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="UnixDateToDT"/>
<link id="PackTime"/>
<link id="UnpackTime"/>
<link id="GetTime"/>
<link id="SetTime"/>
</seealso>
</element>

<element name="UnixDateToDT">
<short>Convert a unix timestamp to a DateTime record </short>
<descr>
<var>DTToUnixDate</var> converts the unix timestamp value in <var>SecsPast</var> to a
DateTime representation in <var>DT</var>. It is an internal function, implemented on Unix platforms,
and should not be used.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="DTToUnixDate"/>
<link id="PackTime"/>
<link id="UnpackTime"/>
<link id="GetTime"/>
<link id="SetTime"/>
</seealso>
</element>


<element name="MSDos">
<short>Execute MS-DOS system call</short>
<descr>
<p>
<var>MSDos</var> executes an operating system call. This is the same as doing a
<var>Intr</var> call with the interrupt number for an os call.
</p>
<remark>
Under non-dos operating systems, this call does nothing. On DOS systems,
this calls interrupt $21.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="Intr"/>
</seealso>
</element>

<element name="PackTime">
<short>Pack DateTime value to a packed-time format.</short>
<descr>
<var>UnPackTime</var> converts the date and time specified in <var>T</var>
to a packed-time format which can be fed to <var>SetFTime</var>.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="SetFTime"/>
<link id="FindFirst"/>
<link id="FindNext"/>
<link id="UnPackTime"/>
</seealso>
<example file="dosex/ex4"/>
</element>


<element name="SetCBreak">
<short>Set Control-Break flag status</short>
<descr>
<p>
<var>SetCBreak</var> sets the status of CTRL-Break checking. When 
<var>BreakValue</var> is <var>false</var>, then dos only checks for the CTRL-Break 
key-press when I/O is performed. When it is set to <var>True</var>, then a 
check is done at every system call.
</p>
<remark>
Under non-dos and non-Amiga operating systems, this call does nothing.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetCBreak"/>
</seealso>
</element>

<element name="SetDate">
<short>Set system date</short>
<descr>
<p>
<var>SetDate</var> sets the system's internal date. <var>Year</var> is a number
between 1980 and 2099.
</p>
<remark>
On a unix machine, there must be root privileges, otherwise this
routine will do nothing. On other unix systems, this call currently
does nothing.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetDate"/>
<link id="SetTime"/>
</seealso>
</element>

<element name="SetFAttr">
<short>Set file attributes</short>
<descr>
<p>
<var>SetFAttr</var> sets the file attributes of the file-variable <var>F</var>.
 <var>F</var> can be a untyped or typed file, or of type <var>Text</var>. <var>F</var> must
have been assigned, but not opened. The attributes can be a sum of the
following constants:
</p>
<ul>
<li> <var>ReadOnly</var></li>
<li> <var>Hidden</var></li>
<li> <var>SysFile</var></li>
<li> <var>VolumeId</var></li>
<li> <var>Directory</var></li>
<li> <var>Archive</var></li>
</ul>
<remark>
Under unix like systems (such as linux and BeOS) the call exists, but is not implemented, 
i.e. it does nothing.
</remark>
</descr>
<errors>
Errors are reported in <var>DosError</var>.
</errors>
<seealso>
<link id="GetFAttr"/>
</seealso>
</element>


<element name="SetFTime">
<short>Set file modification time.</short>
<descr>
<p>
<var>SetFTime</var> sets the modification time of a file,
this time is encoded and must be encoded with <var>PackTime</var>. 
<var>F</var> must be a file type, which has been assigned, and
opened.
</p>
<remark>
Under unix like systems (such as linux and BeOS) the call exists, but is not implemented, 
i.e. it does nothing.
</remark>
</descr>
<errors>
Errors are reported in <var>DosError</var>
</errors>
<seealso>
<link id="GetFTime"/>
<link id="PackTime"/>
<link id="UnPackTime"/>
</seealso>
</element>

<element name="SetIntVec">
<short>Set interrupt vector</short>
<descr>
<p>
<var>SetIntVec</var> sets interrupt vector <var>IntNo</var> to <var>Vector</var>.
<var>Vector</var> should point to an interrupt procedure.
</p>
<remark>
This call does nothing, it is present for compatibility only.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetIntVec"/>
</seealso>
</element>

<element name="SetTime">
<short>Set system time</short>
<descr>
<p>
<var>SetTime</var> sets the system's internal clock. The <var>Hour</var> parameter is
on a 24-hour time scale.
</p>
<remark>
On a linux machine, there must be root privileges, otherwise this
routine will do nothing. On other unix systems, this call currently
does nothing.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetTime"/>
<link id="SetDate"/>
</seealso>
</element>

<element name="SetVerify">
<short>Set verify flag</short>
<descr>
<p>
<var>SetVerify</var> sets the status of the verify flag under dos. When
<var>Verify</var> is <var>True</var>, then dos checks data which are written to disk,
by reading them after writing. If <var>Verify</var> is <var>False</var>, then data
written to disk are not verified.
</p>
<remark>
Under non-dos operating systems (excluding os/2 applications running
under vanilla dos), Verify is always <var>True</var>.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="SetVerify"/>
</seealso>
</element>

<element name="SwapVectors">
<short>Swap interrupt vectors</short>
<descr>
<p>
<var>SwapVectors</var> swaps the contents of the internal table of interrupt 
vectors with the current contents of the interrupt vectors.
This is called typically in before and after an <var>Exec</var> call.
</p>
<remark>
Under certain operating systems, this routine may be implemented
as an empty stub.
</remark>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="Exec"/>
<link id="SetIntVec"/>
</seealso>

</element>
<element name="UnPackTime">
<short>Unpack packed file time to a DateTime value</short>
<descr>
<p>
<var>UnPackTime</var> converts the file-modification time in <var>p</var>
to a <var>DateTime</var> record. The file-modification time can be 
returned by <var>GetFTime</var>, <var>FindFirst</var> or <var>FindNext</var> calls.
</p>
<p>
For an example, see <link id="PackTime"/>.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetFTime"/>
<link id="FindFirst"/>
<link id="FindNext"/>
<link id="PackTime"/>
</seealso>
</element>


</module>
</package>
</fpdoc-descriptions>