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nice(3)
NAME
  nice - Change the scheduling priority of a process

SYNOPSIS
  #include <unistd.h>

  int nice(
	  int increment );

LIBRARY
  Standard C Library (libc)

  Berkeley Compatibility Library (libbsd)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  nice(): XSH4.2

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  increment
      Specifies a value that is added to the current process priority. You
      can specify a negative value.

DESCRIPTION
  The nice() function adds the value specified in the increment parameter to
  the nice value of the calling process. The nice value is a nonnegative
  number; a higher nice value gives the process a lower CPU priority.

  When you are using the Standard C Library version of the nice() function,
  the maximum nice value for a process is 39 (2 * {NZERO} -1) and the minimum
  is 0 (zero). Requests for values outside these limits result in the nice
  value being set to the corresponding limit.

  [XPG4-UNIX]  If execution of the Standard C Library nice() function fails,
  the system does not alter the specified priority.

  Any process can lower its priority (numerically raise its nice value). A
  process must have superuser privileges to raise its priority (numerically
  lower its nice value).

  [Tru64 UNIX]	For backward compatibility, a version of the nice() function
  is supported that allows nice values in the range of -20 to 20. Requests
  for values above or below these limits result in the nice value being set
  to the corresponding limit. To use the backward-compatible version of
  nice(), compile with the Berkeley Compatibility Library (libbsd.a).

RETURN VALUES
  Upon successful completion, the nice() function returns the new nice value
  minus 20 ({NZERO}). Otherwise, the function returns -1 and sets errno to
  indicate the error.

ERRORS
  The Standard C Library version of nice() sets errno to the specified values
  for the following conditions:

  [EPERM]
      The calling process does not have appropriate privilege.

  [Tru64 UNIX]	The libbsd.a version of nice() sets errno to the same values
  as the setpriority() function. For information about possible return values
  for the setpriority() function, see setpriority(2).

SEE ALSO
  Functions: exec(2), getpriority(2), setpriority(2)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for N

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