volution / simple-console-editor

sce -- minimalist console editor (no highlighting, no plugins, no modes, no Emacs)

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SCE -- Simple Console Editor

• About
• Examples
  • Editor examples
  • Pager examples
• Notice

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About

This is my personal plain text editor that I have initially written in a couple of hot summer days of 2008.

Over the years I have made minor enhancements and stability improvements, plus an initial implementation of a browser-like pager.

I have used it since the first days for all my edits, especially for source code, scripting, configuration, in all languages from C to Go, Python to Scheme, Bash to Erlang, HTML / CSS / JavaScript, LaTeX to CommonMark, JSON to XML, all except Java.

The code is written in Python, works with both Python 2.7 and 3.6+, and is only a couple of tousand lines long, ~3.5k for the current version which includes a browser-like pager. However on the down-side the code is quite a mess, but it gets the job done.

It has no dependencies outside the basic Python runtime and the curses library.

It can be deployed as a simple single-file standalone executable, and works on any POSIX-like system from Linux, to OpenBSD and OSX.

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Examples

• Editor examples
  • Invocation syntax
• Pager examples
  • Invocation syntax
  • Choose GPG key identifiers
  • Miscellaneous

Editor examples

Invocation syntax

sce
sce <file>
produce | sce | consume

In the first variant, the editor opens with an empty buffer and allows the user to edit it. One can then use a command like save /tmp/file.txt to save its contents, followed by an exit command.

To run a command just press Ctrl+R and enter the desired command. (As an alternative to the exit command, one can just press Ctrl+X.)

In the second variant, the editor opens the specified file and allows the user to edit it. One can then use a command like save to save its contents, followed by an exit command. (As an alternative to the save command, one can just press Ctrl+S.)

In the third variant, the editor reads all the output produced by produce, opens with an anonymous buffer and allows the user to edit it. One can then use a command like exit to close the editor, and write all the output consumed by consume. This variant basically works with pipes (or plain files) as stdin and stdout, and does not require the usage of a temporary file.

Here are all the supported commands (one just needs to press Ctrl+R to enter them):

• exit -- exits without asking for or executing a save;
• save or save /tmp/file.txt;
• open /tmp/file.txt;
• clear -- empties the current buffer;
• gs text -- search for text; (to find the next match, just press Ctrl+G;)
• gr regex -- searches for a regular expression; (again use Ctrl+G to find the next match;)
• gl number -- go to the line number;
• replace this that -- it will search for the first match, and one has to press Ctrl+N to replace it; to find the next match, press Ctrl+N, then another Ctrl+N to replace it;
• store -- stores the current selection in a temporary file;
• load -- inserts at the current cursor the stored selection from the temporary file;
• (store and load work across invocations, thus allows one to copy-paste between files;)
• pipe command arguments... -- runs the command on the current file or selection, feeding it on stdin, then replacing it with the result from stdout;
• sys i command arguments... -- runs the command, and inserts the output from stdout;
• sys o command arguments... -- runs the command, feeding the current selection on stdin;
• copy -- see Ctrl+D;
• cut -- see Ctrl+K;
• yank -- see Ctrl+Y;
• paste -- see Ctrl+T;

Here are all the supported key bindings / shortcuts:

• up, down, left, right, home, end, page-up, page-down, backspace, delete -- work as expected;
• Ctrl+X -- exits the editor, if the file is untouched or already saved;
• Ctrl+S -- saves the file;
• Ctrl+R -- allows the user to enter a command;
• Ctrl+G -- go to the next match; (as initiated by gs or gr);
• Ctrl+N -- replace the current match, or go to the next replace match; (as initiated by replace;)
• Ctrl+Space -- begins a selection; press Ctrl+Space again to end a selection; the selection is permanent across movements; Ctrl+Space twice to clear the selection;
• Ctrl+D -- copy the selection into the internal buffer;
• Ctrl+K -- cut the selection into the internal buffer;
• Ctrl+Y -- pastes from the internal buffer;
• Ctrl+V -- set a jump marker on the current line;
• Ctrl+Z -- go to the previous marker, and set the current line as the new jump marker; (i.e. with Ctrl+V and Ctrl+Z one can easily jump between two parts of the same file;)
• Ctrl+T -- runs sce-paste, which is a user provided executable, most likely another curses-based application, inserting the output from stdout; (one could for example use fzf to provide various snippets or other "auto-completion" features;)

Pager examples

Invocation syntax

produce | sce-pager <pattern> | consume
produce | sce-pager <pattern> <prefix> <anchor> <suffix> <data> | consume

The four arguments are:

• <pattern> -- a regular expression with captures (^(pub... in the next example), which should match parts of the line that should be highligted;
• <prefix> -- a substitution template (\g<1> in the next example), that will be part of the normal text, right before the anchor;
• <anchor> -- a substitution template ([\g<2>] in the next example), that will be the text for the highlighted anchor;
• <suffix> -- a substitution template (a space in the next example), that will be part of the normal text, right after the anchor;
• <data> -- a substitution template (\g<2> in the next example), that will be the data to be outputed if the current anchor is selected;

The input and output:

• the pager expects that the standard input and output are either a file or a pipe (in fact anything else than a TTY);
• the pager expects that the standard error is a terminal (i.e. a TTY);

Notes:

• the matched part of the string is replaced by concatenating the expansion of prefix, anchor and suffix;
• having both a prefix, suffix, and anchor, allows the user to make "contextual" matches, like in the next example we identify key identifiers as hexademical strings, but only those that appear in the first part of a line starting with pub, but ignoring the GPG key type (which in it turn resembles a hexadecimal string);
• having a different data template, allows the user to present perhaps a shorter version of the data, but still output it in full;
• the syntax of both the regular expressions and substitution patterns are those from the re Python library;
• the regular expression is executed over individual lines, therefore the match will not "wrap" at the line end;
• obviously you can have more than one highlight per line;

Choose GPG key identifiers

Run the following script (by pasting it in your shell):

gpg2 --list-keys --keyid-format short \
| sce-pager '^(pub +[0-9a-zA-Z]+/)([0-9a-fA-F]+) ' '\g<1>' '[\g<2>]' ' ' '\g<2>' \
| cat

Once the pager starts do the following:

• press Tab to move the cursor to the next highlighted key identifier; (the highlights are in yellow;)
• press Enter to select the highlighed key identifier, once you are "over" it with the cursor; (the selected highlights are in red;)
• continue to press Tab to find other key identifiers, and Enter to select them;
• to unselect a highlighted key identifier press Enter once you are "over" it with the cursor;
• press Ctrl+X to exit; the selected key identifiers are printed to the standard output, sorted in lexicographical order;

Miscellaneous

Advanced "tricks":

• you can run various commands by pressing Ctrl+R;
• one of those commands is filter <pattern> <context-lines>, which will show only those lines matching the pattern, plus the choosen number of lines before and after the match; (to clear the filter just run filter;)

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Notice

For details about the copyright and licensing, please consult the notice file in the documentation/licensing folder. (In short the code is licensed under GPL 3 or later.)