1FCHMOD(3P)                 POSIX Programmer's Manual                FCHMOD(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       fchmod — change mode of a file
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SYNOPSIS

16       #include <sys/stat.h>
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18       int fchmod(int fildes, mode_t mode);
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DESCRIPTION

21       The fchmod() function shall be equivalent to chmod()  except  that  the
22       file  whose permissions are changed is specified by the file descriptor
23       fildes.
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25       If fildes references a shared memory object, the fchmod() function need
26       only  affect  the  S_IRUSR,  S_IWUSR,  S_IRGRP,  S_IWGRP,  S_IROTH, and
27       S_IWOTH file permission bits.
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29       If fildes references a typed memory object, the behavior of fchmod() is
30       unspecified.
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32       If fildes refers to a socket, the behavior of fchmod() is unspecified.
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34       If  fildes refers to a STREAM (which is fattach()-ed into the file sys‐
35       tem name space) the call returns successfully, doing nothing.
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RETURN VALUE

38       Upon successful completion, fchmod()  shall  return  0.  Otherwise,  it
39       shall return −1 and set errno to indicate the error.
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ERRORS

42       The fchmod() function shall fail if:
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44       EBADF  The fildes argument is not an open file descriptor.
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46       EPERM  The  effective  user ID does not match the owner of the file and
47              the process does not have appropriate privileges.
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49       EROFS  The file referred to by fildes resides on a read-only file  sys‐
50              tem.
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52       The fchmod() function may fail if:
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54       EINTR  The fchmod() function was interrupted by a signal.
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56       EINVAL The value of the mode argument is invalid.
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58       EINVAL The fildes argument refers to a pipe and the implementation dis‐
59              allows execution of fchmod() on a pipe.
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61       The following sections are informative.
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EXAMPLES

64   Changing the Current Permissions for a File
65       The following example shows how to change the permissions  for  a  file
66       named  /home/cnd/mod1  so that the owner and group have read/write/exe‐
67       cute permissions, but the world only has read/write permissions.
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69           #include <sys/stat.h>
70           #include <fcntl.h>
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72           mode_t mode;
73           int    fildes;
74           ...
75           fildes = open("/home/cnd/mod1", O_RDWR);
76           fchmod(fildes, S_IRWXU | S_IRWXG | S_IROTH | S_IWOTH);
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APPLICATION USAGE

79       None.
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RATIONALE

82       None.
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FUTURE DIRECTIONS

85       None.
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SEE ALSO

88       chmod(), chown(), creat(),  fcntl(),  fstatat(),  fstatvfs(),  mknod(),
89       open(), read(), write()
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91       The Base Definitions volume of POSIX.1‐2008, <sys_stat.h>
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94       Portions  of  this text are reprinted and reproduced in electronic form
95       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
96       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
97       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
98       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
99       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
100       event of any discrepancy between this version and the original IEEE and
101       The Open Group Standard, the original IEEE and The Open Group  Standard
102       is  the  referee document. The original Standard can be obtained online
103       at http://www.unix.org/online.html .
104
105       Any typographical or formatting errors that appear  in  this  page  are
106       most likely to have been introduced during the conversion of the source
107       files to man page format. To report such errors,  see  https://www.ker‐
108       nel.org/doc/man-pages/reporting_bugs.html .
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112IEEE/The Open Group                  2013                           FCHMOD(3P)
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