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Manual Pages  — SETMODE


getmode, setmode – modify mode bits



Standard C Library (libc, -lc)


#include <unistd.h>

getmode(const void *set, mode_t mode);

void *
setmode(const char *mode_str);


The getmode() function returns a copy of the file permission bits mode as altered by the values pointed to by set. While only the mode bits are altered, other parts of the file mode may be examined.

The setmode() function takes an absolute (octal) or symbolic value, as described in chmod(1), as an argument and returns a pointer to mode values to be supplied to getmode(). Because some of the symbolic values are relative to the file creation mask, setmode() may call umask(2). If this occurs, the file creation mask will be restored before setmode() returns. If the calling program changes the value of its file creation mask after calling setmode(), setmode() must be called again if getmode() is to modify future file modes correctly.

If the mode passed to setmode() is invalid or if memory cannot be allocated for the return value, setmode() returns NULL.

The value returned from setmode() is obtained from malloc() and should be returned to the system with free() when the program is done with it, generally after a call to getmode().


The setmode() function may fail and set errno for any of the errors specified for the library routine malloc(3) or strtol(3). In addition, setmode() will fail and set errno to:
  The mode argument does not represent a valid mode.


chmod(1), stat(2), umask(2), malloc(3)


The getmode() and setmode() functions first appeared in BSD 4.4 .


The setmode() function is not thread safe. Files created in other threads while setmode() is being called may be created with a umask of 0.

SETMODE (3) July 18, 2019

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