Escape Sequence

2024-06-27T07:28:13Z

Tobias beyer: Fixed the Example to match the syntax

An '''escape sequence''' is a combination of characters that signifies a command for the [[Terminal|terminal]] rather than a literal combination of characters. In terminals that respond to ANSI character sequences, the escape character has the ASCII value of hexadecimal 1B, octal 33, or decimal 27. A [[Symbol|symbol]] for the escape character can be defined as follows:
esc[0,7] = 27
or:
esc[0,8]=%x1B

=Control Sequences=
Examples in the following tables use the following symbols:
esc[0,7] = 27
text="Text to be displayed"

==Character attributes==

{| class="wikitable"
! colspan="col" | Description
! colspan="col" | Syntax
! colspan="col" | Example
|-
| Bold
| [1m
|
<nowiki>
write sys$output "''esc'[1m''text'''esc'[m"
</nowiki>
|-
| Underscore
| [4m
|
<nowiki>
write sys$output "''esc'[4m''text'''esc'[m"
</nowiki>
|-
| Blink
| [5m
|
<nowiki>
write sys$output "''esc'[5m''text'''esc'[m"
</nowiki>
|-
| Reverse video
| [7m
|
<nowiki>
write sys$output "''esc'[7m''text'''esc'[m"
</nowiki>
|-
| All attributes off
| [0m
|
<nowiki>
write sys$output "''esc'[0m''text'''esc'[m"
</nowiki>
|}

==Line Size==

The attributes below are valid only for the current line.

{| class="wikitable"
! colspan="col" | Description
! colspan="col" | Syntax
! colspan="col" | Example
|-
| Double-height top half
| #3
| Used with #4 to display double-height text:
<nowiki>
$ pipe w "''esc'#3''text'''esc'#3" ; w "''esc'#4''text'''esc'#4"
</nowiki>
|-
| Double-height bottom half
| #4
| Used with #3 to display double-height text:
<nowiki>
$ pipe w "''esc'#3''text'''esc'#3" ; w "''esc'#4''text'''esc'#4"
</nowiki>
|-
| Single width/single height
| #5
|
<nowiki>
$ w "''esc'#5''text'''esc'#5"
</nowiki>
|-
| Double width/double height
| #6
|
<nowiki>
$ w "''esc'#6''text'''esc'#6"
</nowiki>
|}

==Erasing==
{| class="wikitable"
! colspan="col" | Description
! colspan="col" | Syntax
! colspan="col" | Example
|-
| Erases from cursor to end of line
| [K
|
|-
| Erases from the beginning of line to cursor
| [1K
|
<nowiki>
$ write sys$output "''esc'[1K"
</nowiki>
|-
| Erases the line containing cursor
| [2K
|
<nowiki>
$ write sys$output "''esc'[2K"
</nowiki>
|-
| Erases from the cursor to end of screen
| [J
|
<nowiki>
$ write sys$output "''esc'[J"
</nowiki>
|-
| From beginning of screen to cursor
| 1J
|
<nowiki>
$ write sys$output "''esc'1J"
</nowiki>
|-
| Erase the entire screen
| [2J
|
<nowiki>
$ write sys$output "''esc'[2J"
</nowiki>
|}

==Cursor Positioning==
{| class="wikitable"
! colspan="col" | Description
! colspan="col" | Syntax
! colspan="col" | Example
|-
| Move the cursor to line Pl and column Pc
| [Pl;PcH or ESC[Pl;Pcf
|
<nowiki>
$ write sys$output "''esc'[0;0H"
</nowiki>
|-
| Cursor up Pn positions
| [PnA
|
<nowiki>
$ write sys$output "''esc'[1A''text'"
</nowiki>
|-
| Cursor down Pn positions
| [PnB
|
<nowiki>
$ write sys$output "''esc'[1B''text'"
</nowiki>
|-
| Save cursor and attributes
| 7
|
<nowiki>
$ write sys$output "''esc'[1B''esc'7"
</nowiki>
|-
| Cursor forward Pn spaces
| [PnC
|
<nowiki>
$ write sys$output "''esc'[2C''text'"
</nowiki>
|-
| Cursor backward Pn spaces
| [PnD
|
<nowiki>
$ write sys$output "''esc'[2C''text'"
</nowiki>
|-
| Next line
| E
|
<nowiki>
$ write sys$output "''text'''esc'E''text'"
</nowiki>
|-
| Restore cursor and attributes
| ESC 8
|
<nowiki>
$ write sys$output "''esc'[1B''esc'8"
</nowiki>
|}

==Scrolling Region==
The scrolling region can be established with escape code [Pt;Pbr, where Pt is the top line of the scrolling region and Pb is the bottom line.

==Colors==
{| class="wikitable"
! colspan="col" | Description
! colspan="col" | Syntax
! colspan="col" | Example
|-
| Reset (resets the color to default)
| [0m
|
<nowiki>
$ write sys$output "''esc'[30m''text'''esc'[0m"
</nowiki>
|-
| Black
| [30m
|
<nowiki>
$ write sys$output "''esc'[30m''text'''esc'[0m"
</nowiki>
|-
| Red
| [31m
|
<nowiki>
$ write sys$output "''esc'[31m''text'''esc'[0m"
</nowiki>
|-
| Green
| [32m
|
<nowiki>
$ write sys$output "''esc'[32m''text'''esc'[0m"
</nowiki>
|-
| Yellow
| [33m
|
<nowiki>
$ write sys$output "''esc'[33m''text'''esc'[0m"
</nowiki>
|-
| Blue
| [34m
|
<nowiki>
$ write sys$output "''esc'[34m''text'''esc'[0m"
</nowiki>
|-
| Magenta
| [35m
|
<nowiki>
$ write sys$output "''esc'[35m''text'''esc'[0m"
</nowiki>
|-
| Cyan
| [36m
|
<nowiki>
$ write sys$output "''esc'[36m''text'''esc'[0m"
</nowiki>
|-
| White
| [37m
|
<nowiki>
$ write sys$output "''esc'[37m''text'''esc'[0m"
</nowiki>
|}

$SEVERITY

2022-02-18T10:21:27Z

Tobias beyer: Spelling corrected.

'''$SEVERITY''' is a global string [[Symbol|symbol]] that represents the lowest three bits of [[$STATUS]] and therefor determines the severity of the exit condition of the latest command. It can have the following values:

{| class="wikitable"
! colspan="col" | $SEVERITY value
! colspan="col" | Description
|-
| 0
| Warning
|-
| 1
| Successful Execution
|-
| 2
| Error
|-
| 3
| Informational
|-
| 4
| Severe error
|}

VSI OpenVMS Wiki - User contributions [en]

Escape Sequence

$SEVERITY