Simple line-editing and command history library
a day ago

#4 Support for readline-like shortcuts

~ariadnavigo filed ticket on sline todo

a day ago

#sline - Simple line-editing and user input history library

sline is a simple library that easily allows programs to ask for user input with support for line-editing and user input history. It implements a simple VT100 compatible driver that makes it totally independent of third-party libraries. sline also supports UTF-8 in user input.

sline was originally part of scalc.

#Basic usage

A basic use example for sline is provided as sline_test.c in this repository, but in a nutshell, after setting up the terminal with sline_setup(), sline() will read a line from standard input while providing the user with line-editing features. sline_end() restores the terminal back to normal and frees all memory used by sline.

Keep in mind that sline is meant for use with terminals that are compatible with the DEC VT100.

The prototypes for the three subroutines mentioned above are:

 * sline_setup(): Sets the terminal up. The hist parameter sets the size of 
 * user input history buffers; a value of zero (0) will disable the history
 * feature altogether.
int sline_setup(int hist);

 * sline(): Open an sline prompt. User input is stored in buf, reading at most
 * as many characters as represented by size. init stores a default value that
 * may be shown at the prompt; NULL means no default value is shown (i.e. a
 * blank prompt).
int sline(char *buf, int size, const char *init);

 * sline_end(): Restore the terminal to its initial configuration and frees all
 * memory used by sline.
void sline_end(void);

This little snippet illustrates the basic usage of sline:

	/* Set up the terminal without history support */
	if (sline_setup(0) < 0) {
		/* Setup failed, take appropriate actions */

	if ((sline_stat = sline(buf, BUF_SIZE, INIT_STR)) < 0) {
		/* Some error happened, check sline_err for reason. */
	} else {
		/* Process input stored in buf */
	/* Restore terminal back to normal */

For more complex use cases, you may have a look at projects like:

Other procedures in sline allow for checking errors, retrieving user input history, setting the default prompt symbol, etc. You may check the sline(3) and all related manpages cited under its SEE ALSO section for further usage information.


sline is supported on Linux and OpenBSD, and requires:

  1. A C17 compiler
  2. scdoc: to generate the manpage.

Build by using:

$ make

Customize the build process by changing config.mk to suit your needs.


You may install sline by running the following command as root:

# make install

This will install both a static and a dynamic library under $PREFIX/lib, as defined by your environment, or /usr/local/lib by default. Header files will be installed under ${PREFIX}/include, or /usr/local/include by default. The Makefile supports the $DESTDIR variable as well.

Depending on your platform you might need to recreate the linker cache to make the dynamic library available to your system. Usually, this is performed via ldconfig(8), but refer to your system's documentation.


You're very welcome to contribute with patches and discussion by sending an email to ~ariadnavigo/sline-devel@lists.sr.ht. You may want to check out the sline tracker to see where the work is being done right now.

You may stay up-to-date for news about the project by subscribing to the ~ariadnavigo/sline-announce@lists.sr.ht mailing list as well.


sline is published under the MIT License. See LICENSE file for copyright and license details.