EDITLINE(3) | Library Functions Manual | EDITLINE(3)

# NAME

`editline`, `el_init`, `el_end`, `el_reset`, `el_gets`, `el_wgets`, `el_getc`, `el_wgetc`, `el_push`, `el_wpush`, `el_parse`, `el_wparse`, `el_set`, `el_wset`, `el_get`, `el_wget`, `el_source`, `el_resize`, `el_line`, `el_wline`, `el_insertstr`, `el_winsertstr`, `el_deletestr`, `el_wdeletestr`, `history_init`, `history_winit`, `history_end`, `history_wend`, `history`, `history_w`, `tok_init`, `tok_winit`, `tok_end`, `tok_wend`, `tok_reset`, `tok_wreset`, `tok_line`, `tok_wline`, `tok_str`, `tok_wstr` — line editor, history and tokenization functions

# SYNOPSIS

Command Line Editor Library (libedit, -ledit) libcurses
`#include <histedit.h>`

EditLine *
`el_init`(const char *prog, FILE *fin, FILE *fout, FILE *ferr);

void
`el_end`(EditLine *e);

void
`el_reset`(EditLine *e);

const char *
`el_gets`(EditLine *e, int *count);

const wchar_t *
`el_wgets`(EditLine *e, int *count);

int
`el_getc`(EditLine *e, char *ch);

int
`el_wgetc`(EditLine *e, wchar_t *wc);

void
`el_push`(EditLine *e, const char *mbs);

void
`el_wpush`(EditLine *e, const wchar_t *wcs);

int
`el_parse`(EditLine *e, int argc, const char *argv[]);

int
`el_wparse`(EditLine *e, int argc, const wchar_t *argv[]);

int
`el_set`(EditLine *e, int op, ...);

int
`el_wset`(EditLine *e, int op, ...);

int
`el_get`(EditLine *e, int op, ...);

int
`el_wget`(EditLine *e, int op, ...);

int
`el_source`(EditLine *e, const char *file);

void
`el_resize`(EditLine *e);

const LineInfo *
`el_line`(EditLine *e);

const LineInfoW *
`el_wline`(EditLine *e);

int
`el_insertstr`(EditLine *e, const char *str);

int
`el_winsertstr`(EditLine *e, const wchar_t *str);

void
`el_deletestr`(EditLine *e, int count);

void
`el_wdeletestr`(EditLine *e, int count);

History *
`history_init`(void);

HistoryW *
`history_winit`(void);

void
`history_end`(History *h);

void
`history_wend`(HistoryW *h);

int
`history`(History *h, HistEvent *ev, int op, ...);

int
`history_w`(HistoryW *h, HistEventW *ev, int op, ...);

Tokenizer *
`tok_init`(const char *IFS);

TokenizerW *
`tok_winit`(const wchar_t *IFS);

void
`tok_end`(Tokenizer *t);

void
`tok_wend`(TokenizerW *t);

void
`tok_reset`(Tokenizer *t);

void
`tok_wreset`(TokenizerW *t);

int
`tok_line`(Tokenizer *t, const LineInfo *li, int *argc, const char **argv[], int *cursorc, int *cursoro);

int
`tok_wline`(TokenizerW *t, const LineInfoW *li, int *argc, const wchar_t **argv[], int *cursorc, int *cursoro);

int
`tok_str`(Tokenizer *t, const char *str, int *argc, const char **argv[]);

int
`tok_wstr`(TokenizerW *t, const wchar_t *str, int *argc, const wchar_t **argv[]);

# DESCRIPTION

The `editline` library provides generic line editing, history and tokenization functions, similar to those found in sh(1).

The `editline` library is designed to work with blocking I/O only. If the `FIONBIO` ioctl(2) or the `O_NONBLOCK` fcntl(2) is set on fin, `el_gets`() and `el_wgets`() will almost certainly fail with EAGAIN.

The `editline` library respects the `LC_CTYPE` locale set by the application program and never uses setlocale(3) to change the locale. The only locales supported are UTF-8 and the default C or POSIX locale. If any other locale is set, behaviour is undefined.

# LINE EDITING FUNCTIONS

The line editing functions use a common data structure, EditLine, which is created by `el_init`() and freed by `el_end`().

The wide-character functions behave the same way as their narrow counterparts.

The following functions are available:

`el_init`()
  Initialize the line editor, and return a data structure to be used by all other line editing functions, or `NULL` on failure. prog is the name of the invoking program, used when reading the editrc(5) file to determine which settings to use. fin, fout and ferr are the input, output, and error streams (respectively) to use. In this documentation, references to “the tty” are actually to this input/output stream combination.
`el_end`()
  Clean up and finish with e, assumed to have been created with `el_init`().
`el_reset`()
  Reset the tty and the parser. This should be called after an error which may have upset the tty's state.
`el_gets`()
  Read a line from the tty. count is modified to contain the number of characters read. Returns the line read if successful, or `NULL` if no characters were read or if an error occurred. If an error occurred, count is set to -1 and `errno` contains the error code that caused it. The return value may not remain valid across calls to `el_gets`() and must be copied if the data is to be retained.
`el_wgetc`()
  Read a wide character from the tty, respecting the current locale, or from the input queue described in editline(7) if that is not empty, and store it in wc. If an invalid or incomplete character is found, it is discarded, errno is set to `EILSEQ`, and the next character is read and stored in wc. Returns 1 if a valid character was read, 0 on end of file, or -1 on read(2) failure. In the latter case, errno is set to indicate the error.
`el_getc`()
  Read a wide character as described for `el_wgetc`() and return 0 on end of file or -1 on failure. If the wide character can be represented as a single-byte character, convert it with wctob(3), store the result in ch, and return 1; otherwise, set errno to `ERANGE` and return -1. In the C or POSIX locale, this simply reads a byte, but for any other locale, including UTF-8, this is rarely useful.
`el_wpush`()
  Push the wide character string wcs back onto the input queue described in editline(7). If the queue overflows, for example due to a recursive macro, or if an error occurs, for example because wcs is `NULL` or memory allocation fails, the function beeps at the user, but does not report the problem to the caller.
`el_push`()
  Use the current locale to convert the multibyte string mbs to a wide character string, and pass the result to `el_wpush`().
`el_parse`()
  Parses the argv array (which is argc elements in size) to execute builtin `editline` commands. If the command is prefixed with “prog”: then `el_parse`() will only execute the command if “prog” matches the prog argument supplied to `el_init`(). The return value is -1 if the command is unknown, 0 if there was no error or “prog” didn't match, or 1 if the command returned an error. Refer to editrc(5) for more information.
`el_set`()
  Set `editline` parameters. op determines which parameter to set, and each operation has its own parameter list. Returns 0 on success, -1 on failure.

  The following values for op are supported, along with the required argument list:

  `EL_PROMPT`, char *(*f)(EditLine *)
    Define prompt printing function as f, which is to return a string that contains the prompt.
  `EL_PROMPT_ESC`, char *(*f)(EditLine *), char c
    Same as `EL_PROMPT`, but the c argument indicates the start/stop literal prompt character.

    If a start/stop literal character is found in the prompt, the character itself is not printed, but characters after it are printed directly to the terminal without affecting the state of the current line. A subsequent second start/stop literal character ends this behavior. This is typically used to embed literal escape sequences that change the color/style of the terminal in the prompt. `0` unsets it.

  `EL_REFRESH`
    Re-display the current line on the next terminal line.
  `EL_RPROMPT`, char *(*f)(EditLine *)
    Define right side prompt printing function as f, which is to return a string that contains the prompt.
  `EL_RPROMPT_ESC`, char *(*f)(EditLine *), char c
    Define the right prompt printing function but with a literal escape character.
  `EL_TERMINAL`, const char *type
    Define terminal type of the tty to be type, or to `TERM` if type is `NULL`.
  `EL_EDITOR`, const char *mode
    Set editing mode to mode, which must be one of “emacs” or “vi”.
  `EL_SIGNAL`, int flag
    If flag is non-zero, `editline` will install its own signal handler for the following signals when reading command input: `SIGCONT`, `SIGHUP`, `SIGINT`, `SIGQUIT`, `SIGSTOP`, `SIGTERM`, `SIGTSTP`, and `SIGWINCH`. Otherwise, the current signal handlers will be used.
  `EL_BIND`, const char *, ..., `NULL`
    Perform the `bind` builtin command. Refer to editrc(5) for more information.
  `EL_ECHOTC`, const char *, ..., `NULL`
    Perform the `echotc` builtin command. Refer to editrc(5) for more information.
  `EL_SETTC`, const char *, ..., `NULL`
    Perform the `settc` builtin command. Refer to editrc(5) for more information.
  `EL_SETTY`, const char *, ..., `NULL`
    Perform the `setty` builtin command. Refer to editrc(5) for more information.
  `EL_TELLTC`, const char *, ..., `NULL`
    Perform the `telltc` builtin command. Refer to editrc(5) for more information.
  `EL_ADDFN`, const char *name, const char *help, unsigned char (*func)(EditLine *e, int ch)
    Add a user defined function, `func`(), referred to as name which is invoked when a key which is bound to name is entered. help is a description of name. At invocation time, ch is the key which caused the invocation. The return value of `func`() should be one of:
    `CC_NORM`
      Add a normal character.
    `CC_NEWLINE`
      End of line was entered.
    `CC_EOF`
      EOF was entered.
    `CC_ARGHACK`
      Expecting further command input as arguments, do nothing visually.
    `CC_REFRESH`
      Refresh display.
    `CC_REFRESH_BEEP`
      Refresh display, and beep.
    `CC_CURSOR`
      Cursor moved, so update and perform `CC_REFRESH`.
    `CC_REDISPLAY`
      Redisplay entire input line. This is useful if a key binding outputs extra information.
    `CC_ERROR`
      An error occurred. Beep, and flush tty.
    `CC_FATAL`
      Fatal error, reset tty to known state.
  `EL_HIST`, History *(*func)(History *, int op, ...), const char *ptr
    Defines which history function to use, which is usually `history`(). ptr should be the value returned by `history_init`().
  `EL_EDITMODE`, int flag
    If flag is non-zero, editing is enabled (the default). Note that this is only an indication, and does not affect the operation of `editline`. At this time, it is the caller's responsibility to check this (using `el_get`()) to determine if editing should be enabled or not.
  `EL_UNBUFFERED`, int flag
    If flag is zero, unbuffered mode is disabled (the default). In unbuffered mode, `el_gets`() will return immediately after processing a single character.
  `EL_GETCFN`, el_rfunc_t f
    Whenever reading a character, use the function
    int `f`(EditLine *e, wchar_t *wc);
    which stores the character in wc and returns 1 on success, 0 on end of file, or -1 on I/O or encoding errors. Functions internally using it include `el_wgets`(), `el_wgetc`(), `el_gets`(), and `el_getc`(). Initially, a builtin function is installed, and replacing it is discouraged because writing such a function is very error prone. The builtin function can be restored at any time by passing the special value `EL_BUILTIN_GETCFN` instead of a function pointer.
  `EL_CLIENTDATA`, void *data
    Register data to be associated with this EditLine structure. It can be retrieved with the corresponding `el_get`() call.
  `EL_SETFP`, int fd, FILE *fp
    Set the current `editline` file pointer for “input” fd = `0`, “output” fd = `1`, or “error” fd = `2` from fp.
`el_get`()
  Get `editline` parameters. op determines which parameter to retrieve into result. Returns 0 if successful, -1 otherwise.

  The following values for op are supported, along with actual type of result:

  `EL_PROMPT`, char *(*f)(EditLine *), char *c
    Set f to a pointer to the function that displays the prompt. If c is not `NULL`, set it to the start/stop literal prompt character.
  `EL_RPROMPT`, char *(*f)(EditLine *), char *c
    Set f to a pointer to the function that displays the prompt. If c is not `NULL`, set it to the start/stop literal prompt character.
  `EL_EDITOR`, const char **n
    Set the name of the editor in n, which will be one of “emacs” or “vi”.
  `EL_GETTC`, const char *name, void *value
    If name is a valid termcap(5) capability, set value to the current value of that capability.
  `EL_SIGNAL`, int *s
    Set s to non-zero if `editline` has installed private signal handlers (see `el_get`() above).
  `EL_EDITMODE`, int *c
    Set c to non-zero if editing is enabled.
  `EL_GETCFN`, el_rfunc_t *f
    Set f to a pointer to the function that reads characters, or to `EL_BUILTIN_GETCFN` if the builtin function is in use.
  `EL_CLIENTDATA`, void **data
    Set data to the previously registered client data set by an `el_set`() call.
  `EL_UNBUFFERED`, int *c
    Set c to non-zero if unbuffered mode is enabled.
  `EL_PREP_TERM`, int
    Sets or clears terminal editing mode.
  `EL_GETFP`, int fd, FILE **fp
    Set fp to the current `editline` file pointer for “input” fd = `0`, “output” fd = `1`, or “error” fd = `2`.
`el_source`()
  Initialize `editline` by reading the contents of file. `el_parse`() is called for each line in file. If file is `NULL`, try $HOME/.editrc. Refer to editrc(5) for details on the format of file. `el_source`() returns 0 on success and -1 on error.
`el_resize`()
  Must be called if the terminal size changes. If `EL_SIGNAL` has been set with `el_set`(), then this is done automatically. Otherwise, it's the responsibility of the application to call `el_resize`() on the appropriate occasions.
`el_line`()
  Return the editing information for the current line in a LineInfo structure, which is defined as follows:

      typedef struct lineinfo {
          const char *buffer;    /* address of buffer */
          const char *cursor;    /* address of cursor */
          const char *lastchar;  /* address of last character */
      } LineInfo;

  buffer is not NUL terminated. This function may be called after `el_gets`() to obtain the LineInfo structure pertaining to line returned by that function, and from within user defined functions added with `EL_ADDFN`.

`el_insertstr`()
  Insert str into the line at the cursor. Returns -1 if str is empty or won't fit, and 0 otherwise.
`el_deletestr`()
  Delete count characters before the cursor.

# HISTORY LIST FUNCTIONS

The history functions use a common data structure, History, which is created by `history_init`() and freed by `history_end`().

The following functions are available:

`history_init`()
  Initialize the history list, and return a data structure to be used by all other history list functions, or `NULL` on failure.
`history_end`()
  Clean up and finish with h, assumed to have been created with `history_init`().
`history`()
  Perform operation op on the history list, with optional arguments as needed by the operation. ev is changed accordingly to operation. The following values for op are supported, along with the required argument list:
  `H_SETSIZE`, int size
    Set size of history to size elements.
  `H_GETSIZE`
    Get number of events currently in history.
  `H_END`
    Cleans up and finishes with h, assumed to be created with `history_init`().
  `H_CLEAR`
    Clear the history.
  `H_FUNC`, void *ptr, history_gfun_t first, history_gfun_t next, history_gfun_t last, history_gfun_t prev, history_gfun_t curr, history_sfun_t set, history_vfun_t clear, history_efun_t enter, history_efun_t add
    Define functions to perform various history operations. ptr is the argument given to a function when it's invoked.
  `H_FIRST`
    Return the first element in the history.
  `H_LAST`
    Return the last element in the history.
  `H_PREV`
    Return the previous element in the history. It is newer than the current one.
  `H_NEXT`
    Return the next element in the history. It is older than the current one.
  `H_CURR`
    Return the current element in the history.
  `H_SET`
    Set the cursor to point to the requested element.
  `H_ADD`, const char *str
    Append str to the current element of the history, or perform the `H_ENTER` operation with argument str if there is no current element.
  `H_APPEND`, const char *str
    Append str to the last new element of the history.
  `H_ENTER`, const char *str
    Add str as a new element to the history and, if necessary, removing the oldest entry to keep the list to the created size. If `H_SETUNIQUE` has been called with a non-zero argument, the element will not be entered into the history if its contents match the ones of the current history element. If the element is entered, `history`() returns 1; if it is ignored as a duplicate, returns 0. Finally `history`() returns -1 if an error occurred.
  `H_PREV_STR`, const char *str
    Return the closest previous event that starts with str.
  `H_NEXT_STR`, const char *str
    Return the closest next event that starts with str.
  `H_PREV_EVENT`, int e
    Return the previous event numbered e.
  `H_NEXT_EVENT`, int e
    Return the next event numbered e.
  `H_LOAD`, const char *file
    Load the history list stored in file.
  `H_SAVE`, const char *file
    Save the history list to file.
  `H_SAVE_FP`, FILE *fp
    Save the history list to the opened FILE pointer fp.
  `H_SETUNIQUE`, int unique
    Set flag that adjacent identical event strings should not be entered into the history.
  `H_GETUNIQUE`
    Retrieve the current setting if adjacent identical elements should be entered into the history.
  `H_DEL`, int e
    Delete the event numbered e. This function is only provided for readline(3) compatibility. The caller is responsible for free'ing the string in the returned HistEvent.

  `history`() returns >= 0 if the operation op succeeds. Otherwise, -1 is returned and ev is updated to contain more details about the error.

# TOKENIZATION FUNCTIONS

The tokenization functions use a common data structure, Tokenizer, which is created by `tok_init`() and freed by `tok_end`().

The following functions are available:

`tok_init`()
  Initialize the tokenizer, and return a data structure to be used by all other tokenizer functions. IFS contains the Input Field Separators, which defaults to ⟨space⟩, ⟨tab⟩, and ⟨newline⟩ if `NULL`.
`tok_end`()
  Clean up and finish with t, assumed to have been created with `tok_init`().
`tok_reset`()
  Reset the tokenizer state. Use after a line has been successfully tokenized by `tok_line`() or `tok_str`() and before a new line is to be tokenized.
`tok_line`()
  Tokenize li, If successful, modify: argv to contain the words, argc to contain the number of words, cursorc (if not `NULL`) to contain the index of the word containing the cursor, and cursoro (if not `NULL`) to contain the offset within argv[cursorc] of the cursor.

  Returns 0 if successful, -1 for an internal error, 1 for an unmatched single quote, 2 for an unmatched double quote, and 3 for a backslash quoted ⟨newline⟩. A positive exit code indicates that another line should be read and tokenization attempted again.

`tok_str`()
  A simpler form of `tok_line`(); str is a NUL terminated string to tokenize.

# SEE ALSO

sh(1), curses(3), signal(3), editrc(5), termcap(5), editline(7)

# HISTORY

The `editline` library first appeared in 4.4BSD. `CC_REDISPLAY` appeared in NetBSD 1.3. `CC_REFRESH_BEEP`, `EL_EDITMODE` and the readline emulation appeared in NetBSD 1.4. `EL_RPROMPT` appeared in NetBSD 1.5.

# AUTHORS

The `editline` library was written by Christos Zoulas. Luke Mewburn wrote this manual and implemented `CC_REDISPLAY`, `CC_REFRESH_BEEP`, `EL_EDITMODE`, and `EL_RPROMPT`. Jaromir Dolecek implemented the readline emulation. Johny Mattsson implemented wide-character support.

# BUGS

At this time, it is the responsibility of the caller to check the result of the `EL_EDITMODE` operation of `el_get`() (after an `el_source`() or `el_parse`()) to determine if `editline` should be used for further input. I.e., `EL_EDITMODE` is purely an indication of the result of the most recent editrc(5) `edit` command.

June 5, 2025 | Debian