NAME

       getline, getdelim - delimited string input

SYNOPSIS

       #include <stdio.h>

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

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getline(), getdelim():
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE

DESCRIPTION

       getline()  reads  an entire line from stream, storing the address of the buffer containing
       the text into *lineptr.  The buffer is null-terminated and includes the newline character,
       if one was found.

       If  *lineptr  is  set  to  NULL before the call, then getline() will allocate a buffer for
       storing the line.  This buffer should be freed by  the  user  program  even  if  getline()
       failed.

       Alternatively,   before   calling   getline(),   *lineptr  can  contain  a  pointer  to  a
       malloc(3)-allocated buffer *n bytes in size.  If the buffer is not large  enough  to  hold
       the line, getline() resizes it with realloc(3), updating *lineptr and *n as necessary.

       In  either  case,  on  a  successful  call, *lineptr and *n will be updated to reflect the
       buffer address and allocated size respectively.

       getdelim() works like getline(), except that a line delimiter other than  newline  can  be
       specified  as  the  delimiter  argument.   As with getline(), a delimiter character is not
       added if one was not present in the input before end of file was reached.

RETURN VALUE

       On success, getline() and getdelim() return the number of characters read,  including  the
       delimiter  character,  but not including the terminating null byte ('\0').  This value can
       be used to handle embedded null bytes in the line read.

       Both functions return -1 on failure to read a line (including end-of-file condition).   In
       the event of a failure, errno is set to indicate the error.

ERRORS

       EINVAL Bad arguments (n or lineptr is NULL, or stream is not valid).

       ENOMEM Allocation or reallocation of the line buffer failed.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │getline(), getdelim()                                          │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       Both  getline()  and getdelim() were originally GNU extensions.  They were standardized in
       POSIX.1-2008.

EXAMPLES

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

       int
       main(int argc, char *argv[])
       {
           FILE *stream;
           char *line = NULL;
           size_t len = 0;
           ssize_t nread;

           if (argc != 2) {
               fprintf(stderr, "Usage: %s <file>\n", argv[0]);
               exit(EXIT_FAILURE);
           }

           stream = fopen(argv[1], "r");
           if (stream == NULL) {
               perror("fopen");
               exit(EXIT_FAILURE);
           }

           while ((nread = getline(&line, &len, stream)) != -1) {
               printf("Retrieved line of length %zd:\n", nread);
               fwrite(line, nread, 1, stdout);
           }

           free(line);
           fclose(stream);
           exit(EXIT_SUCCESS);
       }

SEE ALSO

       read(2), fgets(3), fopen(3), fread(3), scanf(3)

COLOPHON

       This page is part of release 5.13 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.