January
7
Linux: Terminal Control Escape Sequences
[ Status | Setup |
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Erasing | Printing |
Keyboard | Colours ]
Many computer terminals and terminal emulators support colour and
cursor control through a system of escape sequences. One such standard
is commonly referred to as ANSI Colour. Several terminal
specifications are based on the ANSI colour standard, including VT100.
The following is a partial listing of the VT100 control set.
<ESC> represents the ASCII “escape”
character, 0x1B. Bracketed tags represent modifiable decimal
parameters; eg. {ROW} would be replaced by a row
number.
Device Status
The following codes are
used for reporting terminal/display settings, and vary depending on the
implementation:
Query Device Code <ESC>[c
- Requests a
Report Device Coderesponse from
the device.
Report Device Code <ESC>[{code}0c
- Generated by the device in response to
Query Devicerequest.
Code
Query Device Status <ESC>[5n
- Requests a
Report Device Statusresponse
from the device.
Report Device OK <ESC>[0n
- Generated by the device in response to a
Query Devicerequest; indicates that device is functioning
Status
correctly.
Report Device Failure <ESC>[3n
- Generated by the device in response to a
Query Devicerequest; indicates that device is functioning
Status
improperly.
Query Cursor Position <ESC>[6n
- Requests a
Report Cursor Positionresponse
from the device.
Report Cursor Position <ESC>[{ROW};{COLUMN}R
- Generated by the device in response to a
Query Cursorrequest; reports current cursor position.
Position
Terminal Setup
The
h and l codes are used for
setting terminal/display mode, and vary depending on the implementation.
Line Wrap is one of the few setup codes that tend to be used
consistently:
Reset Device <ESC>c
- Reset all terminal settings to default.
Enable Line Wrap <ESC>[7h
- Text wraps to next line if longer than the length of the display
area.
Disable Line Wrap <ESC>[7l
- Disables line wrapping.
Fonts
Some terminals support multiple
fonts: normal/bold, swiss/italic, etc. There are a variety of special
codes for certain terminals; the following are fairly standard:
Font Set G0 <ESC>(
- Set default font.
Font Set G1 <ESC>)
- Set alternate font.
Cursor Control
Cursor Home <ESC>[{ROW};{COLUMN}H
- Sets the cursor position where subsequent text will begin. If no
row/column parameters are provided (ie.<ESC>[H),
the cursor will move to the home position, at the upper left
of the screen.
Cursor Up <ESC>[{COUNT}A
- Moves the cursor up by COUNT rows; the default count is
1.
Cursor Down <ESC>[{COUNT}B
- Moves the cursor down by COUNT rows; the default count is
1.
Cursor Forward <ESC>[{COUNT}C
- Moves the cursor forward by COUNT columns; the
default count is 1.
Cursor Backward <ESC>[{COUNT}D
- Moves the cursor backward by COUNT columns; the
default count is 1.
Force Cursor Position <ESC>[{ROW};{COLUMN}f
- Identical to
Cursor Home.
Save Cursor <ESC>[s
- Save current cursor position.
Unsave Cursor <ESC>[u
- Restores cursor position after a
Save Cursor.
Save Cursor & Attrs <ESC>7
- Save current cursor position.
Restore Cursor & Attrs <ESC>8
- Restores cursor position after a
Save Cursor.
Scrolling
Scroll Screen <ESC>[r
- Enable scrolling for entire display.
Scroll Screen <ESC>[{start};{end}r
- Enable scrolling from row
{start}to row
{end}.
Scroll Down <ESC>D
- Scroll display down one line.
Scroll Up <ESC>M
- Scroll display up one line.
Tab Control
Set Tab <ESC>H
- Sets a tab at the current position.
Clear Tab <ESC>[g
- Clears tab at the current position.
Clear All Tabs <ESC>[3g
- Clears all tabs.
Erasing Text
Erase End of Line <ESC>[K
- Erases from the current cursor position to the end of the current
line.
Erase Start of Line <ESC>[1K
- Erases from the current cursor position to the start of the
current line.
Erase Line <ESC>[2K
- Erases the entire current line.
Erase Down <ESC>[J
- Erases the screen from the current line down to the bottom of the
screen.
Erase Up <ESC>[1J
- Erases the screen from the current line up to the top of the
screen.
Erase Screen <ESC>[2J
- Erases the screen with the background colour and moves the cursor
to home.
Printing
Some terminals support local
printing:
Print Screen <ESC>[i
- Print the current screen.
Print Line <ESC>[1i
- Print the current line.
Stop Print Log <ESC>[4i
- Disable log.
Start Print Log <ESC>[5i
- Start log; all received text is echoed to a printer.
Define Key
Set Key Definition <ESC>[{key};"{string}"p
- Associates a string of text to a keyboard key.
{key}
indicates the key by its ASCII value in decimal.
Set Display Attributes
Set Attribute Mode <ESC>[{attr1};...;{attrn}m
- Sets multiple display attribute settings. The following lists
standard attributes:0 Reset all attributes 1 Bright 2 Dim 4 Underscore 5 Blink 7 Reverse 8 Hidden Foreground Colours 30 Black 31 Red 32 Green 33 Yellow 34 Blue 35 Magenta 36 Cyan 37 White Background Colours 40 Black 41 Red 42 Green 43 Yellow 44 Blue 45 Magenta 46 Cyan 47 White
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Setup | Fonts |
Cursor | Scrolling |
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Printing | Keyboard |
Colours ]
-By: John