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Unix's Ctrl-D is a TTY control character and nothing to do with a soft EOF character stored in a file. |
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{{Short description|Non-printing computer data item}}
A '''substitute character''' (␚) is a [[control character]] that is used in the place of a character that is recognized to be invalid or in error or that cannot be represented on a given device. It is also used as an escape sequence for some programming languages.▼
{{Redirect|␦|the Arabic question mark|؟|the rhetorical question or irony mark|⸮}}
{{Redirect|Ctrl+Z|the "undo" function|Undo}}
{{Use dmy dates|date=February 2020|cs1-dates=y}}
{{Use list-defined references|date=December 2021}}
▲
In the [[ASCII
==Uses==
===End of file===
{{Main|End-of-file}}
In [[CP/M]], [[86-DOS]], [[MS-DOS]], [[PC
While no longer technically required to indicate the end of a file, as of 2017, many text editors{{which|date=October 2023}} and program languages
Some programming languages (e.g.
Character 26 was used to mark "End of file" even
===Other uses===
In [[Unix]]-like operating systems, this character is typically used in [[Shell (computing)|shell]]s as a way for the user to [[SIGTSTP|suspend]] the currently executing interactive process.<ref name="
The
In many GUIs and applications, {{
== Representation ==
*
*
*
*
*
==References==▼
{{reflist}}▼
* [[Federal Standard 1037C]]▼
==See also==
* [[C0 and C1 control codes]] ([[ISO 646]])
* [[U+FFFD]] (Unicode replacement character �)
* [[Access key]]
* [[Control-C]]
Line 44 ⟶ 46:
* [[Control-\]]
* [[Keyboard shortcut]]
* [[List of file signatures]]
* {{mono|[[.notdef]]}}, a symbol (sometimes called by the slang term ''tofu'') used to represent a missing character
** [[Noto fonts]], a Google project to eliminate missing characters
▲==References==
<ref name="DRI_1979_CPM20-IG">{{cite book |title=CP/M 2.0 Interface Guide |chapter=2. Operating System Call Conventions |date=1979 |edition=1 |publisher=[[Digital Research]] |location=Pacific Grove, California, USA |page=5 |url=http://bitsavers.org/pdf/digitalResearch/cpm/2.0/CPM_2_0_Interface_Guide_1979.pdf |access-date=2020-02-28 |url-status=live |archive-url=https://web.archive.org/web/20200228175812/http://bitsavers.org/pdf/digitalResearch/cpm/2.0/CPM_2_0_Interface_Guide_1979.pdf |archive-date=2020-02-28 |quote=[...] The end of an [[ASCII]] file is denoted by a [[control-Z]] character (1AH) or a real end of file, returned by the [[CP/M]] read operation. Control-Z characters embedded within machine code files (e.g., [[COM file]]s) are ignored, however, and the end of file condition returned by CP/M is used to terminate read operations. [...]}} (56 pages)</ref>
<ref name="Hogan_1982_CP/M">{{cite book |title=Osborne CP/M User Guide - For All CP/M Users |chapter=3. CP/M Transient Commands |author-first=Thom |author-last=Hogan |publisher=[[A. Osborne/McGraw-Hill]] |date=1982 |edition=2 |location=Berkeley, California, USA <!-- |lccn=87-65432??? --> |isbn=0-931988-82-9 |page=[https://archive.org/details/osborne-cpm-users-guide_2nd-ed/page/n87 74] |url=https://archive.org/details/osborne-cpm-users-guide_2nd-ed |access-date=2020-02-28 |quote=[...] [[CP/M]] marks the end of an [[ASCII]] file by placing a [[CONTROL-z]] character in the file after the last data character. If the file contains an exact multiple of 128 characters, in which case adding the CONTROL-Z would waste 127 characters, CP/M does not do so. Use of the CONTROL-Z character as the [[end-of-file marker]] is possible because CONTROL-z is seldom used as data in ASCII files. In a non-ASCII file, however, CONTROL-Z is just as likely to occur as any other character. Therefore, it cannot be used as the end-of-file marker. CP/M uses a different method to mark the end of a non-ASCII file. CP/M assumes it has reached the end of the file when it has read the last record (basic unit of disk space) allocated to the file. The disk directory entry for each file contains a list of the disk records allocated to that file. This method relies on the size of the file, rather than its content, to locate the end of the file. [...]}} [https://archive.org/stream/osborne-cpm-users-guide_2nd-ed/OsborneCpmUsersGuideSecondEdition_djvu.txt][https://archive.org/download/osborne-cpm-users-guide_2nd-ed/OsborneCpmUsersGuideSecondEdition.pdf]</ref>
<ref name="DEC_1965_PDP-6">{{cite book |title=PDP-6 Multiprogramming System Manual |chapter=Table of IO Device Characteristics - Console or Teletypewriters |id=DEC-6-0-EX-SYS-UM-IP-PRE00 |publisher=[[Digital Equipment Corporation]] (DEC) |publication-place=Maynard, Massachusetts, USA |date=1965 |page=43 |url=http://bitsavers.trailing-edge.com/pdf/dec/pdp6/DEC-6-0-EX-SYS-UM-IP-PRE00_Multiprogramming_System_Manual_1965.pdf |access-date=2014-07-10 |url-status=live |archive-url=https://web.archive.org/web/20140714140253/http://bitsavers.trailing-edge.com/pdf/dec/pdp6/DEC-6-0-EX-SYS-UM-IP-PRE00_Multiprogramming_System_Manual_1965.pdf |archive-date=2014-07-14}} (1+84+10 pages)</ref>
<ref name="DEC_1969_PDP-10">{{cite book |title=PDP-10 Reference Handbook: Communicating with the Monitor - Time-Sharing Monitors |volume=3 |chapter=5.1.1.1. Device Dependent Functions - Data Modes - Full-Duplex Software A(ASCII) and AL(ASCII Line) |publisher=[[Digital Equipment Corporation]] (DEC) |date=1969 |pages=5-3 – 5-6 [5-5 (431)] |url=http://bitsavers.org/pdf/dec/pdp10/1970_PDP-10_Ref/1970PDP10Ref_Part3.pdf |access-date=2014-07-10 |url-status=live |archive-url=https://web.archive.org/web/20111115083418/http://www.bitsavers.org/pdf/dec/pdp10/1970_PDP-10_Ref/1970PDP10Ref_Part3.pdf |archive-date=2011-11-15}} (207 pages)</ref>
<ref name="Microsoft_126449">{{cite web |title=Keyboard shortcuts for Windows |work=Microsoft Support |publisher=[[Microsoft]] |url=http://support.microsoft.com/kb/126449 |access-date=2012-06-02}}</ref>
<ref name="Elliott_1998_CPM14">{{cite web |author-first=John C. |author-last=Elliott |date=1998 |title=CP/M 1.4 disc formats |url=http://www.seasip.info/Cpm/format14.html |access-date=2021-11-18 |url-status=live |archive-url=https://web.archive.org/web/20201114231913/http://www.seasip.info/Cpm/format14.html |archive-date=2020-11-14}}</ref>
<ref name="Elliott_1998_CPM22">{{cite web |author-first=John C. |author-last=Elliott |date=1998 |title=CP/M 2.2 disc formats |url=http://www.seasip.info/Cpm/format22.html |access-date=2021-11-18 |url-status=live |archive-url=https://web.archive.org/web/20201105204828/http://www.seasip.info/Cpm/format22.html |archive-date=2020-11-05}}</ref>
<ref name="Elliott_1998_CPM31">{{cite web |author-first=John C. |author-last=Elliott |date=1998 |title=CP/M 3.1 disc formats |url=http://www.seasip.info/Cpm/format31.html |access-date=2021-11-18 |url-status=live |archive-url=https://web.archive.org/web/20211026154048/https://www.seasip.info/Cpm/format31.html |archive-date=2021-10-26}}</ref>
<ref name="Elliott_1998_DOSPLUS">{{cite web |author-first=John C. |author-last=Elliott |date=1998 |title=CP/M 4.1 disc formats |url=http://www.seasip.info/Cpm/format41.html |access-date=2021-11-18 |url-status=live |archive-url=https://web.archive.org/web/20201105174304/http://www.seasip.info/Cpm/format41.html |archive-date=2020-11-05}}</ref>
<ref name="UW_Unix">{{cite web |title=Quick Reference: Unix Commands |work=IT Connect |publisher=[[University of Washington]] |url=http://www.washington.edu/computing/unix/unixqr.html |access-date=2012-06-02}}</ref>
<ref name="Mastpoint_2016_CSV-1203">[http://www.mastpoint.com/csv-1203 CSV-1203 format specification] {{Webarchive|url=http://arquivo.pt/wayback/20160516100434/http://www.mastpoint.com/csv-1203 |date=2016-05-16}}</ref>
<ref name="Unicode_USC">[http://unicode.org/reports/tr36/#Text_Comparison Unicode Security Considerations report]</ref>
}}
==Further reading==
▲* [[Federal Standard 1037C]]
[[Category:Control characters]]
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