Read from a file without moving the file pointer
#include <unistd.h> ssize_t pread(int filedes, void *buff, size_t nbytes, off_t offset ); ssize_t pread64( int filedes, void *buff, size_t nbytes, off64_t offset );
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The pread() function performs the same action as read(), except that it reads from a given position in the file without changing the file pointer.
The pread() function reads up to the maximum offset value that can be represented in an off_t for regular files. An attempt to perform a pread() on a file that's incapable of seeking results in an error.
The pread64() function is a 64-bit version of pread().
The number of bytes actually read, or -1 if an error occurred (errno is set).
pread() is POSIX 1003.1 XSI; pread64() is Large-file support
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