dterc

dterc is the language used in dte configuration files (~/.dte/rc) and also in the command mode of the editor (Alt+x). The syntax of the language is quite similar to shell, but much simpler.

Commands are separated either by a newline or ; character. To make a command span multiple lines in an rc file, escape the newline (put \ at the end of the line).

Rc files can contain comments at the start of a line. Comments begin with a # character and can be indented, but they can't be put on the same line as a command.

Commands can contain environment variables. Variables always expand into a single argument even if they contain whitespace. Variables inside single or double quotes are NOT expanded. This makes it possible to bind keys to commands that contain variables (inside single or double quotes), which will be expanded just before the command is executed.

Example:

alias x "run chmod 755 $FILE"

$FILE is expanded when the alias x is executed. The command works even if $FILE contains whitespace.

Special variables

These variables are always defined and override environment variables of the same name.

$FILE

The absolute filename of the current buffer (or an empty string if unsaved).

$RFILE

The relative filename of the current buffer (or an empty string if unsaved).

$FILEDIR

The directory part of $FILE.

$FILETYPE

The value of the filetype option for the current buffer.

$LINENO

The line number of the cursor in the current buffer.

$COLNO

The column number of the cursor in the current buffer.

$WORD

The selected text or the word under the cursor.

$DTE_HOME

The user configuration directory. This is either the value of $DTE_HOME when the editor first started, or the default value ($HOME/.dte).

Single quoted strings

Single quoted strings can't contain single quotes or escaped characters.

Double quoted strings

Double quoted strings may contain the following escapes:

\a, \b, \t, \n, \v, \f, \r
Control characters (same as in C)
\e
Escape character
\\
Backslash
\"
Double quote
\x0a
Hexadecimal byte value 0x0A (note that \x00 is not supported, because strings are null-terminated)
\u20ac
Four hex digit Unicode code point U+20AC
\U000020ac
Eight hex digit Unicode code point U+20AC

Commands

Configuration Commands

Configuration commands are used to customize certain aspects of the editor, for example adding key bindings, setting options, etc. These are the only commands allowed in user config files.

alias name [command]

Create an alias name for command. If no command is given then any existing alias for name is removed.

Aliases can be used in command mode or bound to keys, just as normal commands can. When aliases are used in place of commands, they are first recursively expanded (to allow aliases of aliases) and any additional arguments are then added to the end of the expanded command.

For example, if the following alias is created:

alias read 'pipe-from cat'

this can then be invoked as read file.txt, which will expand to the command pipe-from cat file.txt and thus cause file.txt to be inserted into the current buffer.

bind [-cns] key [command]

Bind command to key. If no command is given then any existing binding for key is removed.

Special keys:

Modifiers:

Ctrl:
C-x (or ^X)
Alt:
M-x
Shift:
S-left
Super:
s-left
Hyper:
H-left

The key is bound in normal mode by default, unless one or more of the following flags are used:

-c
Add binding for command mode
-n
Add binding for normal mode
-s
Add binding for search mode

The commands available in normal mode are the ones listed in the main sections of this manual.

The commands available in command/search modes are as follows:

Most of these commands behave in a similar fashion to the normal mode commands of the same name. The exceptions to this have been given a short description above.

Most of the command flags also behave similarly to the normal mode equivalents, except for accept -H, which accepts the current text without adding a history entry and accept -e (search mode only) which escapes all regex special characters before performing a (plain-text) search.

See also:

set [-gl] option [value] ...

Set value for option. Value can be omitted for boolean option to set it true. Multiple options can be set at once but then value must be given for every option.

There are three kinds of options.

  1. Global options.

  2. Local options. These are file specific options. Each open file has its own copies of the option values.

  3. Options that have both global and local values. The Global value is just a default local value for opened files and is never used for anything else. Changing the global value does not affect any already opened files.

By default set changes both global and local values.

-g
Change only global option value
-l
Change only local option value of current file

In configuration files only global options can be set (no need to specify the -g flag).

See also: toggle and option commands.

setenv name [value]

Set (or unset) environment variable.

hi [-c] [name] [fg-color [bg-color]] [attribute]...

Set highlight color.

The name argument can be a token name defined by a dte-syntax file or one of the following, built-in highlight names:

The fg-color and bg-color arguments can be one of the following:

Colors 16 to 231 correspond to R/G/B colors and 232 to 255 are grayscale values (see https://www.ditig.com/publications/256-colors-cheat-sheet for more details).

If the terminal has limited support for rendering colors, the fg-color and bg-color arguments will fall back to the nearest supported color (unless the -c flag is used; see below).

The attribute argument(s) can be any combination of the following:

The color and attribute value keep is useful in selected text to keep fg-color and attributes and change only bg-color.

NOTE: Because keep is both a color and an attribute you need to specify both fg-color and bg-color if you want to set the keep attribute.

Unset fg/bg colors are inherited from highlight color default. If you don't set fg/bg for the highlight color default then terminal's default fg/bg is used.

If hi is run without any arguments, all highlight colors are removed and a baseline set of defaults is then loaded (as if by running include -b on the built-in color/reset config).

-c
Do nothing at all if the terminal can't display fg-color and/or bg-color with full precision (this can be used to set up tiered color schemes that use the best supported colors automatically)

ft [-b|-c|-f|-i] filetype string...

Add a filetype association. Filetypes are used to determine which syntax highlighter and local options to use when opening files.

By default string is interpreted as one or more filename extensions.

-b
Interpret string as a file basename
-c
Interpret string as a regex pattern and match against the contents of the first line of the file
-f
Interpret string as a regex pattern and match against the full (absolute) filename
-i
Interpret string as a command interpreter name and match against the Unix shebang line (after removing any path prefix and/or version suffix)

Examples:

ft c c h
ft -b make Makefile GNUmakefile
ft -c xml '<\?xml'
ft -f mail '/tmpmsg-.*\.txt$'
ft -i lua lua luajit

See also:

option [-r] filetype option value...

Add automatic option for filetype (as previously registered with the ft command). Automatic options are set when files are are opened.

-r
Interpret filetype argument as a regex pattern instead of a filetype and match against full filenames

include [-bq] file

Read and execute commands from file.

-b
Read built-in file instead of reading from the filesystem
-q
Don't show an error message if file doesn't exist

Note: "built-in files" are config files bundled into the program binary. See the -B and -b flags in the dte man page and the show include command for more information.

errorfmt [-i] compiler [regexp] [file|line|column|message|_]...

Register a regex pattern, for later use with the compile command.

When the compile command is invoked with a specific compiler name, the regexp pattern(s) previously registered with that name are used to parse messages from it's program output.

The regexp pattern should contain as many capture groups as there are extra arguments. These capture groups are used to parse the file, line, message, etc. from the output and, if possible, jump to the corresponding file position. To use parentheses in regexp but ignore the capture, use _ as the extra argument.

Running errorfmt multiple times with the same compiler name appends each regexp to a list. When running compile, the entries in the specified list are checked for a match in the same order they were added.

If only 1 argument (i.e. compiler) is given, all patterns previously added for that compiler name will be removed.

For a basic example of usage, see the output of dte -b compiler/go.

-i
Ignore this error

Editor Commands

quit [-f|-p] [exitcode]

Quit the editor.

The exit status of the process is set to exitcode, which can be in the range 0..125, or defaults to 0 if unspecified.

-f
Force quit, even if there are unsaved files
-p
Prompt for confirmation if there are unsaved files

suspend

Suspend the editor (run fg in the shell to resume).

cd directory

Change the working directory and update $PWD and $OLDPWD. Running cd - changes to the previous directory ($OLDPWD).

command [text]

Enter command mode. If text is given then it is written to the command line (see the default ^L key binding for why this is useful).

refresh

Trigger a full redraw of the screen.

Buffer Management Commands

open [-g|-t] [-e encoding] [filename]...

Open file. If filename is omitted, a new file is opened.

-e encoding
Set file encoding (see iconv -l for list of supported encodings)
-g
Perform glob expansion on filename
-t
Mark buffer as "temporary" (always closeable, without warnings for "unsaved changes")

save [-fp] [-d|-u] [-b|-B] [-e encoding] [filename]

Save current buffer.

-b
Write byte order mark (BOM)
-B
Don't write byte order mark
-d
Save with DOS/CRLF line-endings
-f
Force saving read-only file
-u
Save with Unix/LF line-endings
-p
Open a command prompt if there's no specified or existing filename
-e encoding
Set file encoding (see iconv -l for list of supported encodings)

See also: newline and utf8-bom global options

close [-qw] [-f|-p]

Close file.

-f
Force close file, even if it has unsaved changes
-p
Prompt for confirmation if the file has unsaved changes
-q
Quit if closing the last open file
-w
Close parent window if closing its last contained file

next

Display next file.

prev

Display previous file.

view N|last

Display Nth or last open file.

move-tab N|left|right

Move current tab to position N or 1 position left or right.

Window Management Commands

wsplit [-bghr] [-n|-t|filename...]

Split the current window.

filename arguments will be opened in a manner similar to the open command. If there are no filename arguments, the contents of the new window will be an additional view of the current buffer.

-b
Add new window before current instead of after
-g
Perform glob expansion on filename
-h
Split horizontally instead of vertically
-n
Create a new, empty buffer
-r
Split root instead of current window
-t
Create a new, empty buffer and mark it as "temporary" (always closeable, without warnings for "unsaved changes")

wclose [-f|-p]

Close window.

-f
Force close window, even if it contains unsaved files
-p
Prompt for confirmation if there are unsaved files in the window

wnext

Next window.

wprev

Previous window.

wresize [-h|-v] [N|+N|-- -N]

If no parameter given, equalize window sizes in current frame.

-h
Resize horizontally
-v
Resize vertically
N
Set size of current window to N columns/rows
+N
Increase size of current window by N columns/rows
-N
Decrease size of current window by N columns/rows (use -- to prevent the minus symbol being parsed as an option flag, e.g. wresize -- -5)

wflip

Change from vertical layout to horizontal and vice versa.

wswap

Swap positions of this and next frame.

Movement Commands

Movement commands are used to move the cursor position.

Several of these commands also have -c and -l flags to allow creating character/line selections. These 2 flags are noted in the command summaries below, but are only described once, as follows:

-c
Select characters
-l
Select whole lines

left [-c]

Move one column left.

Move one column right.

up [-c|-l]

Move one line up.

down [-c|-l]

Move one line down.

pgup [-c|-l]

Move one page up.

pgdown [-c|-l]

Move one page down.

blkup [-c|-l]

Move one block up.

Note: a "block", in this context, is somewhat akin to a paragraph. Blocks are delimited by one or more blank lines

blkdown [-c|-l]

Move one block down.

word-fwd [-cs]

Move forward one word.

-s
Skip special characters

word-bwd [-cs]

Move backward one word.

-s
Skip special characters

bol [-c] [-s|-t]

Move to beginning of current line.

-s
Move to beginning of indented text or beginning of line, depending on current cursor position
-t
Like -s, but with the additional behavior of moving back and forth between the two positions

eol [-c]

Move to end of current line.

bof [-c|-l]

Move to beginning of file.

eof [-c|-l]

Move to end of file.

bolsf [-c|-l]

Incrementally move to beginning of line, then beginning of screen, then beginning of file.

eolsf [-c|-l]

Incrementally move to end of line, then end of screen, then end of file.

scroll-up

Scroll view up one line. Keeps cursor position unchanged if possible.

scroll-down

Scroll view down one line. Keeps cursor position unchanged if possible.

scroll-pgup

Scroll one page up. Cursor position relative to top of screen is maintained. See also pgup.

scroll-pgdown

Scroll one page down. Cursor position relative to top of screen is maintained. See also pgdown.

center-view

Center view to cursor.

match-bracket

Move to the bracket character paired with the one under the cursor. The character under the cursor should be one of {}[]()<>.

If no flags or just -r and no pattern given then dte changes to search mode, where you can type a regular expression to search.

-H
Don't add pattern to search history
-n
Search next
-p
Search previous
-r
Start searching backwards
-w
Search word under cursor

line lineno[,colno]

Move the cursor to the line number specified by lineno and (optionally) the column number specified by colno. The delimiter between the two numbers can either be a comma (,) or a colon (:).

Examples:

line 19
line 20,15
line 20:15

bookmark [-r]

Save the current file/cursor location to a stack.

-r
Jump back to the previous location (and pop it off the stack)

tag [-r|tag]

Save the current file/cursor location to a stack and jump to the location of tag. If the tag argument is not given, the word under the cursor is used instead (unless -r is used).

The location for tag is determined by parsing a tags file from the current directory, or any of its parent directories. These files are expected be encoded in ctags format.

-r
Jump back to the previous location (and pop it off the stack)

Note: the saving of the cursor location described above is much the same as running bookmark and tag -r is identical to bookmark -r.

See also: msg command.

msg [-n|-p|number]

Display and/or navigate messages, as generated by the compile and tag commands. If the activated message has an associated file location, the file will be opened and the cursor moved to the appropriate position.

If no -n or -p flag or number argument is given, the current message will be displayed.

-n
Next message
-p
Previous message

Editing Commands

cut

Cut current line or selection.

copy [-bikp]

Copy current line or selection.

-b
Copy to system clipboard
-i
Copy to internal copy buffer (this is the default, if no -bip flags are used)
-k
Keep selection (by default, selections are lost after copying)
-p
Copy to system "primary selection"

Note that the -b and -p flags depend upon the terminal supporting "OSC 52" escape sequences. If the terminal lacks this support, these flags will simply do nothing. OSC 52 sends data over the wire, so it can be used over SSH and still work as expected, unlike most other methods of copying to the system clipboard.

The -i, -b and -p flags can be used together, to allow copying to multiple targets in a single command. For example:

copy -ib

paste [-m] [-a|-c]

Insert text previously copied by the copy or cut commands.

If the text to be inserted was copied from a whole-line selection (e.g. down -l; copy) or as a whole, single line (e.g. unselect; copy) the default behaviour is to insert the text at the start of the line below the cursor.

-a
Paste above the cursor (instead of below), if pasting whole lines
-c
Always paste directly at the cursor position, even when pasting whole lines (instead of below/above the cursor)
-m
Move after the pasted text

undo [-m]

Undo latest change.

-m
Move to the change location, without undoing it

redo [choice]

Redo changes done by the undo command. If there are multiple possibilities a message is displayed:

Redoing newest (2) of 2 possible changes.

If the change was not the one you wanted, just run undo and then, for example, redo 1.

clear

Clear current line.

-i
Do not auto-indent the line after clearing

join [delimiter]

Join selection or next line to current using delimiter. If delimiter is not provided, a space is used.

new-line [-a]

Insert empty line below current line.

-a
Insert above current line, instead of below

delete

Delete character after cursor (or selection).

erase

Delete character before cursor (or selection).

delete-eol [-n]

Delete to end of line.

-n
Delete newline if cursor is at end of line

erase-bol

Erase to beginning of line.

delete-word [-s]

Delete word after cursor.

-s
Be more "aggressive"

erase-word [-s]

Erase word before cursor.

-s
Be more "aggressive"

delete-line

Delete current line.

case [-l|-u]

Change text case. The default is to change lower case to upper case and vice versa.

-l
Lower case
-u
Upper case

insert [-k|-m] text

Insert text into the buffer.

-k
Insert one character at a time, as if manually typed (normally text is inserted exactly as specified, but this option allows it to be affected by special input handling like auto-indents, whitespace trimming, line-by-line undo, etc.)
-m
Move after inserted text

replace [-bcgi] pattern replacement

Replace all instances of text matching pattern with the replacement text. Matching is confined to the current selection, if there is one.

The pattern argument is a POSIX extended regex.

The replacement argument is treated like a template and may contain several, special substitutions:

Note: extra care must be taken when using double quotes for the pattern argument, since double quoted arguments have their own (higher precedence) backslash sequences.

-b
Use basic (instead of extended) regex syntax
-c
Ask for confirmation before each replacement
-g
Replace all matches for each line (instead of just the first)
-i
Ignore case

Examples:

replace ^ #
replace 'Hello World' '& (Hallo Welt)'
replace "[ \t]+$" ''
replace -cg '([^ ]+) +([^ ]+)' '\2 \1'

shift count

Shift current or selected lines by count indentation levels. Count is usually -1 (decrease indent) or 1 (increase indent).

To specify a negative number, it's necessary to first disable option parsing with --, e.g. shift -- -1.

wrap-paragraph [width]

Format the current selection or paragraph under the cursor. If paragraph width is not given then the text-width option is used.

This command merges the selection into one paragraph. To format multiple paragraphs use the external fmt program with the filter command, e.g. filter fmt -w 60.

select [-kl]

Enter selection mode. All basic movement commands while in this mode extend the selected area, until either the unselect command is used (e.g. by pressing Esc) or some other operation (e.g. delete, insert, etc.) clears the selection.

Note: A better way to create selections is to hold the Shift key while moving the cursor. The select command exists mostly as a fallback, for terminals with limited key binding support.

-k
Keep existing selections
-l
Select whole lines

unselect

Cancel selection.

External Commands

exec [-pstmn] [-ioe action]... command [argument]...

Execute external command, with custom actions for standard streams. The -i, -o and -e options represent standard input, output and error respectively and each one can be given a specific action, as described below.

The following action arguments are supported by all -ioe options:

Actions for stdin (-i):

Actions for stdout (-o):

Actions for stderr (-e):

-i action
Specify standard input action
-o action
Specify standard output action
-e action
Specify standard error action
-p
Display "press any key to continue" prompt
-s
Don't yield terminal control to child processes and transparently convert tty actions to null (use this to avoid screen flicker when command doesn't need terminal access)
-t
Cancel the effects of -s (last one wins)
-m
Move cursor after inserted text (if any)
-n
Strip newline from end of inserted text (if any)

For convenience, there are several built-in aliases to simplify common uses of exec:

alias filter 'exec -s -i buffer -o buffer -e errmsg'
alias pipe-from 'exec -s -o buffer -e errmsg'
alias pipe-to 'exec -s -i buffer -e errmsg'
alias run 'exec'
alias eval 'exec -o eval'
alias exec-open 'exec -o open'
alias exec-tag 'exec -o tag'
alias exec-msg 'exec -o msg -i msg'

Examples:

filter sort -r
filter sh -c 'tr a-z A-Z | sed s/foo/bar/'
pipe-to xsel -b
exec-open -s find . -type f -name *.h
exec-open -s git ls-files --modified
exec-open fzf -m --reverse
exec-tag -s echo main
exec-tag sh -c 'readtags -l | cut -f1 | sort | uniq | fzf --reverse'

When passing the buffer through a filter command, the cursor is moved to line 1 and the whole contents is replaced with the output. It may be useful to save and restore the cursor position, in cases where line numbers remain mostly unchanged. This can be done by wrapping the command with bookmark and bookmark -r, e.g.:

bookmark; filter expand --tabs=4; bookmark -r

Note that command is executed directly using execvp. To use shell features like pipes or redirection, use a shell interpreter as the command (see second example above). If complex commands become difficult to read (e.g. due to nested/escaped quotes), it's recommended to create external scripts and execute those instead.

compile [-1ps] errorfmt command [argument]...

Run external command and collect output messages. This can be used to run e.g. compilers, build systems, code search utilities, etc. and then jump to a file/line position for each message.

The errorfmt argument corresponds to a regex capture pattern previously specified by the errorfmt command. After command exits successfully, parsed messages can be navigated using the msg command.

-1
Read error messages from stdout instead of stderr
-p
Display "Press any key to continue" prompt
-s
Don't echo command output to the terminal during execution; just silently collect messages (use this to avoid screen flicker, e.g. for commands that typically complete quickly)

See also: errorfmt and msg commands.

Other Commands

repeat count command [argument]...

Run command count times.

toggle [-gv] option [values]...

Toggle option. If list of values is not given then the option must be either boolean or enum.

-g
toggle global option instead of local
-v
display new value

If option has both local and global values then local is toggled unless -g is used.

show [-c] type [key]

Display current values for various configurable types.

The type argument can be one of:

alias
Show command aliases
bind
Show key bindings
color
Show highlight colors
command
Show command history
env
Show environment variables
errorfmt
Show compiler error formats
ft
Show filetype associations
hi
Show highlight colors
include
Show built-in configs
macro
Show last recorded macro
msg
Show messages
option
Show option values and automatic option entries
search
Show search history
set
Show option values
setenv
Show environment variables, in terms of the setenv command
wsplit
Show window dimensions

The key argument is the name of the entry to look up (e.g. the alias name). If this argument is omitted, the full list of entries of the specified type will be displayed in a new buffer.

Note: the majority of type arguments correspond to a command of the same name and some type arguments don't take any key argument.

-c
write output to the command line (for most type arguments) or to the current buffer (when type is errorfmt or include)

macro action

Record and replay command macros.

The action argument can be one of:

record
Begin recording
stop
Stop recording
toggle
Toggle recording on/off
cancel
Stop recording, without overwriting the previous macro
play
Replay the previously recorded macro

Once a macro has been recorded, it can be viewed in text form by running show macro.

Options

Options can be changed using the set command. Enumerated options can also be toggled. To see which options are enumerated, type "toggle " in command mode and press the tab key. You can also use the option command to set default options for specific file types.

Global options

false
Search is case-insensitive
true
Search is case-sensitive
auto
If search string contains an uppercase letter search is case-sensitive, otherwise it is case-insensitive

display-special [false]

Display special characters.

esc-timeout [100] 0...2000

When single escape is read from the terminal dte waits some time before treating the escape as a single keypress. The timeout value is in milliseconds.

Too long timeout makes escape key feel slow and too small timeout can cause escape sequences of for example arrow keys to be split and treated as multiple key presses.

filesize-limit [250]

Refuse to open any file with a size larger than this value (in mebibytes). Useful to prevent accidentally opening very large files, which can take a long time on some systems.

lock-files [true]

Keep a record of open files, so that a warning can be shown if the same file is accidentally opened in multiple dte processes.

See also: the FILES section in the dte man page.

newline [unix]

Whether to use LF (unix) or CRLF (dos) line-endings in newly created files.

Note: buffers opened from existing files will have their newline type detected automatically.

optimize-true-color [true]

If set to true, this option will cause the hi command to automatically replace 24-bit #RRGGBB colors with palette colors 16-255, but only if there's an exact color match among the default, extended palette colors.

This allows defining color schemes in #RRGGBB notation while still sending the shortest possible escape sequence to the terminal.

Note: this optimization only works if the terminal has not been configured with custom values for colors 16-255. If you have changed these extended palette colors, you should set this option to false.

select-cursor-char [true]

Whether to include the character under the cursor in selections.

scroll-margin [0]

Minimum number of lines to keep visible before and after cursor.

set-window-title [false]

Set the window title to the filename of the current buffer (if the terminal supports it).

show-line-numbers [false]

Show line numbers.

statusline-left [" %f%s%m%s%r%s%M"]

Format string for the left aligned part of status line.

%f
Filename
%m
Prints * if file has been modified since last save
%r
Prints RO for read-only buffers or TMP for temporary buffers
%y
Cursor row
%Y
Total rows in file
%x
Cursor display column
%X
Cursor column as characters. If it differs from cursor display column then both are shown (e.g. 2-9)
%p
Position in percentage
%E
File encoding
%b
Prints BOM if file has a byte order mark
%M
Miscellaneous status information
%n
Line-ending (LF or CRLF)
%N
Line-ending (only if CRLF)
%s
Separator (a single space, unless the preceding format character expanded to an empty string)
%S
Like %s, but 3 spaces instead of 1
%t
File type
%u
Hexadecimal Unicode value value of character under cursor
%o
Prints OVR or INS for overwrite mode on or off respectively
%%
Literal %

statusline-right [" %y,%X %u %o %E%s%b%s%n %t %p "]

Format string for the right aligned part of status line.

tab-bar [true]

Whether to show the tab-bar at the top of each window.

utf8-bom [false]

Whether to write a byte order mark (BOM) in newly created UTF-8 files.

Note: buffers opened from existing UTF-8 files will have their BOM (or lack thereof) preserved as it was, unless overridden by the save command.

Local options

brace-indent [false]

Scan for { and } characters when calculating indentation size. Depends on the auto-indent option.

filetype [none]

Type of file. Value must be previously registered using the ft command.

indent-regex [""]

If this regex pattern matches the current line when enter is pressed and auto-indent is true then indentation is increased. Set to "" to disable.

Local and global options

The global values for these options serve as the default values for local (per-file) options.

auto-indent [true]

Automatically insert indentation when pressing enter. Indentation is copied from previous non-empty line. If also the indent-regex local option is set then indentation is automatically increased if the regular expression matches current line.

detect-indent [""]

Comma-separated list of indent widths (1-8) to detect automatically when a file is opened. Set to "" to disable. Tab indentation is detected if the value is not "". Adjusts the following options if indentation style is detected: emulate-tab, expand-tab, indent-width.

Example:

set detect-indent 2,3,4,8

emulate-tab [false]

Make delete, erase and moving left and right inside indentation feel as if there were tabs instead of spaces.

expand-tab [false]

Convert tab to spaces on insert.

file-history [true]

Save and restore cursor positions for previously opened files.

See also: the FILES section in the dte man page.

indent-width [8]

Size of indentation in spaces.

overwrite [false]

If set to true, typing will overwrite existing characters within current line instead of inserting before them.

syntax [true]

Use syntax highlighting.

tab-width [8]

Width of tab. Recommended value is 8. If you use other indentation size than 8 you should use spaces to indent.

text-width [72]

Preferred width of text. Used as the default argument for the wrap-paragraph command.

ws-error [special]

Comma-separated list of flags that describe which whitespace errors should be highlighted. Set to "" to disable.

auto-indent
If the expand-tab option is enabled then this is the same as tab-after-indent,tab-indent. Otherwise it's the same as space-indent.
space-align
Highlight spaces used for alignment after tab indents as errors.
space-indent
Highlight space indents as errors. Note that this still allows using less than tab-width spaces at the end of indentation for alignment.
tab-after-indent
Highlight tabs used anywhere other than indentation as errors.
tab-indent
Highlight tabs in indentation as errors. If you set this you most likely want to set "tab-after-indent" too.
special
Display all characters that look like regular space as errors. One of these characters is no-break space (U+00A0), which is often accidentally typed (AltGr+space in some keyboard layouts).
trailing
Highlight trailing whitespace characters at the end of lines as errors.