1GETLINE(3) Linux Programmer's Manual GETLINE(3)
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6 getline, getdelim - delimited string input
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9 #define _GNU_SOURCE
10 #include <stdio.h>
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12 ssize_t getline(char **lineptr, size_t *n, FILE *stream);
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14 ssize_t getdelim(char **lineptr, size_t *n, int delim, FILE *stream);
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17 getline() reads an entire line from stream, storing the address of the
18 buffer containing the text into *lineptr. The buffer is null-termi‐
19 nated and includes the newline character, if one was found.
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21 If *lineptr is NULL, then getline() will allocate a buffer for storing
22 the line, which should be freed by the user program. (The value in *n
23 is ignored.)
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25 Alternatively, before calling getline(), *lineptr can contain a pointer
26 to a malloc(3)-allocated buffer *n bytes in size. If the buffer is not
27 large enough to hold the line, getline() resizes it with realloc(3),
28 updating *lineptr and *n as necessary.
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30 In either case, on a successful call, *lineptr and *n will be updated
31 to reflect the buffer address and allocated size respectively.
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33 getdelim() works like getline(), except a line delimiter other than
34 newline can be specified as the delimiter argument. As with getline(),
35 a delimiter character is not added if one was not present in the input
36 before end of file was reached.
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39 On success, getline() and getdelim() return the number of characters
40 read, including the delimiter character, but not including the termi‐
41 nating null byte. This value can be used to handle embedded null bytes
42 in the line read.
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44 Both functions return -1 on failure to read a line (including end of
45 file condition).
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48 EINVAL Bad arguments (n or lineptr is NULL, or stream is not valid).
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51 Both getline() and getdelim() are GNU extensions. They are available
52 since libc 4.6.27.
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55 #define _GNU_SOURCE
56 #include <stdio.h>
57 #include <stdlib.h>
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59 int
60 main(void)
61 {
62 FILE * fp;
63 char * line = NULL;
64 size_t len = 0;
65 ssize_t read;
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67 fp = fopen("/etc/motd", "r");
68 if (fp == NULL)
69 exit(EXIT_FAILURE);
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71 while ((read = getline(&line, &len, fp)) != -1) {
72 printf("Retrieved line of length %zu :\n", read);
73 printf("%s", line);
74 }
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76 if (line)
77 free(line);
78 exit(EXIT_SUCCESS);
79 }
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82 read(2), fgets(3), fopen(3), fread(3), gets(3), scanf(3), fea‐
83 ture_test_macros(7)
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86 This page is part of release 3.22 of the Linux man-pages project. A
87 description of the project, and information about reporting bugs, can
88 be found at http://www.kernel.org/doc/man-pages/.
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92GNU 2006-05-17 GETLINE(3)