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Top Forums Shell Programming and Scripting For loop inside awk to read and print contents of files Post 302817931 by Corona688 on Thursday 6th of June 2013 04:29:45 PM
Old 06-06-2013
Sorry about that, awk's getline always confuses me. It uses neither the C nor C++ convention for return value on these things, but some weird hybrid of both, causing the usual while(getline) most programmers expect to become an infinite loop as well.

Last edited by Corona688; 06-06-2013 at 05:37 PM..
 

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GETDELIM(3)						   BSD Library Functions Manual 					       GETDELIM(3)

NAME
getdelim, getline -- read a delimited record from a stream LIBRARY
Standard C Library (libc, -lc) 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 reads from the stream until it encounters a character matching delimiter, storing the input in *lineptr. The buffer is NUL-terminated and includes the delimiter. The delimiter character must be representable as an unsigned char. If *n is non-zero, then *lineptr must be pre-allocated to at least *n bytes. The buffer should be allocated dynamically; it must be possible to free(3) *lineptr. getdelim() ensures that *lineptr is large enough to hold the input, updating *n to reflect the new size. The getline() function is equivalent to getdelim() with delimiter set to the newline character. RETURN VALUES
The getdelim() and getline() functions return the number of characters read, including the delimiter. If no characters were read and the stream is at end-of-file, the functions return -1. If an error occurs, the functions return -1 and the global variable errno is set to indi- cate the error. The functions do not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred. EXAMPLES
The following code fragment reads lines from a file and writes them to standard output. char *line = NULL; size_t linesize = 0; ssize_t linelen; while ((linelen = getline(&line, &linesize, fp)) != -1) fwrite(line, linelen, 1, stdout); if (ferror(fp)) perror("getline"); ERRORS
[EINVAL] lineptr or n is a NULL pointer. [EOVERFLOW] More than SSIZE_MAX characters were read without encountering the delimiter. The getdelim() and getline() functions may also fail and set errno for any of the errors specified in the routines fflush(3), malloc(3), read(2), stat(2), or realloc(3). SEE ALSO
ferror(3), fgets(3), fopen(3) STANDARDS
The getdelim() and getline() functions conform to IEEE Std 1003.1-2008 (``POSIX.1''). BSD
June 30, 2010 BSD
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