<html> <head> <title>ftruncate</title> <body bgcolor=#ffffff> <h2 align=center>ftruncate</h2> <h4 align=center>OS/161 Reference Manual</h4> <h3>Name</h3> ftruncate - set size of a file <h3>Library</h3> Standard C Library (libc, -lc) <h3>Synopsis</h3> #include <unistd.h><br> <br> int<br> ftruncate(int <em>fd</em>, off_t <em>filesize</em>); <h3>Description</h3> ftruncate forcibly sets the size of the file referred to by <em>fd</em> to <em>filesize</em>. If this expands the file, the new data appears as if it is zero-filled. If this shrinks the file, the excess data is discarded. <p> The file must be open for write. <h3>Return Values</h3> On success, ftruncate returns 0. On error, -1 is returned, and <A HREF=errno.html>errno</A> is set according to the error encountered. <h3>Errors</h3> The following error codes should be returned under the conditions given. Other error codes may be returned for other errors not mentioned here. <blockquote><table width=90%> <td width=10%> </td><td> </td></tr> <tr><td>EBADF</td> <td><em>fd</em> is not a valid file handle, or it is not open for writing.</td></tr> <tr><td>EIO</td> <td>A hard I/O error occurred.</td></tr> <tr><td>EFAULT</td> <td><em>buf</em> points to an invalid address.</td></tr> </table></blockquote> </body> </html>