PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       getdelim, getline — read a delimited record from stream

SYNOPSIS

       #include <stdio.h>

       ssize_t getdelim(char **restrict lineptr, size_t *restrict n,
           int delimiter, FILE *restrict stream);
       ssize_t getline(char **restrict lineptr, size_t *restrict n,
           FILE *restrict stream);

DESCRIPTION

       The  getdelim()  function  shall read from stream until it encounters a character matching
       the delimiter character. The delimiter  argument  is  an  int,  the  value  of  which  the
       application  shall  ensure is a character representable as an unsigned char of equal value
       that terminates the read process. If the delimiter  argument  has  any  other  value,  the
       behavior is undefined.

       The application shall ensure that *lineptr is a valid argument that could be passed to the
       free() function. If *n is non-zero, the application  shall  ensure  that  *lineptr  either
       points to an object of size at least *n bytes, or is a null pointer.

       The size of the object pointed to by *lineptr shall be increased to fit the incoming line,
       if it isn't already large enough, including room for the delimiter and a terminating  NUL.
       The  characters read, including any delimiter, shall be stored in the string pointed to by
       the lineptr argument, and a terminating NUL added when the delimiter or  end  of  file  is
       encountered.

       The  getline()  function shall be equivalent to the getdelim() function with the delimiter
       character equal to the <newline> character.

       The getdelim() and getline() functions may mark the last data access timestamp of the file
       associated  with  stream  for  update.  The last data access timestamp shall be marked for
       update by the first successful execution of fgetc(), fgets(), fread(),  fscanf(),  getc(),
       getchar(),  getdelim(),  getline(),  gets(), or scanf() using stream that returns data not
       supplied by a prior call to ungetc().

RETURN VALUE

       Upon successful completion, the getline() and getdelim() functions shall return the number
       of  characters  written  into  the  buffer,  including  the delimiter character if one was
       encountered before EOF, but excluding the terminating NUL character. If no characters were
       read,  and the end-of-file indicator for the stream is set, or if the stream is at end-of-
       file, the end-of-file indicator for the stream shall be set and the function shall  return
       −1.  If an error occurs, the error indicator for the stream shall be set, and the function
       shall return −1 and set errno to indicate the error.

ERRORS

       For the conditions under which the getdelim() and getline() functions shall fail  and  may
       fail, refer to fgetc().

       In addition, these functions shall fail if:

       EINVAL lineptr or n is a null pointer.

       ENOMEM Insufficient memory is available.

       These functions may fail if:

       EOVERFLOW
              More  than  {SSIZE_MAX}  characters  were  read  without encountering the delimiter
              character.

       The following sections are informative.

EXAMPLES

           #include <stdio.h>
           #include <stdlib.h>

           int main(void)
           {
               FILE *fp;
               char *line = NULL;
               size_t len = 0;
               ssize_t read;
               fp = fopen("/etc/motd", "r");
               if (fp == NULL)
                   exit(1);
               while ((read = getline(&line, &len, fp)) != -1) {
                   printf("Retrieved line of length %zu :\n", read);
                   printf("%s", line);
               }
               if (ferror(fp)) {
                   /* handle error */
               }
               free(line);
               fclose(fp);
               return 0;
           }

APPLICATION USAGE

       Setting *lineptr to a null pointer and *n to zero are allowed and  a  recommended  way  to
       start parsing a file.

       The  ferror() or feof() functions should be used to distinguish between an error condition
       and an end-of-file condition.

       Although a NUL terminator is always supplied after the line,  note  that  strlen(*lineptr)
       will be smaller than the return value if the line contains embedded NUL characters.

RATIONALE

       These  functions  are  widely used to solve the problem that the fgets() function has with
       long lines. The functions automatically enlarge the target buffers if  needed.  These  are
       especially useful since they reduce code needed for applications.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.5, Standard I/O Streams, fgetc(), fgets(), free()

       The Base Definitions volume of POSIX.1‐2008, <stdio.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2013 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX),  The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical  Corrigendum  1  applied.)  In  the  event of any
       discrepancy between this version and the original IEEE and The Open  Group  Standard,  the
       original  IEEE  and The Open Group Standard is the referee document. The original Standard
       can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .