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Annotation of coherent/a/usr/man/COHERENT/fork, revision 1.1.1.1

1.1       root        1: 
                      2: 
                      3: fork()                 COHERENT System Call                fork()
                      4: 
                      5: 
                      6: 
                      7: 
                      8: Create a new process
                      9: 
                     10: fork()
                     11: 
                     12: In  the COHERENT  system,  many processes  may  be active  simul-
                     13: taneously.   fork creates  a new  process; the  new process  is a
                     14: duplicate  of  the  requesting  process.   In practice,  the  new
                     15: process often issues a call to execute yet another new program.
                     16: 
                     17: The  process  that issues  the  fork call  is  termed the  parent
                     18: process,  and  the  newly  forked  process  is termed  the  child
                     19: process.  fork returns the  process id of the newly created child
                     20: to the  parent process,  and returns  zero to the  child process.
                     21: The parent  may call wait to suspend itself  until the child ter-
                     22: minates.
                     23: 
                     24: The following  parts of the environment of  a process are exactly
                     25: duplicated by a fork call:
                     26: 
                     27: *  Open files and their seek positions
                     28: 
                     29: *  Current working and root directories
                     30: 
                     31: *  The file creation mask
                     32: 
                     33: *  The values of all signals
                     34: 
                     35: *  The alarm clock setting
                     36: 
                     37: *  Code, data, and stack segments
                     38: 
                     39: The system  normally makes  a fresh copy  of the code,  data, and
                     40: stack segments  for the child  process.  One advantage  of shared
                     41: text processes is that they do not need to copy the code segment.
                     42: It is write protected, and therefore may be shared.
                     43: 
                     44: ***** Example *****
                     45: 
                     46: For an example of how to use this call, see pipe.
                     47: 
                     48: ***** See Also *****
                     49: 
                     50: alarm(),  COHERENT system  calls, execl(),  exit(),  sh, umask(),
                     51: wait()
                     52: 
                     53: ***** Diagnostics *****
                     54: 
                     55: fork returns  -1 on failure, which  usually involves insufficient
                     56: system resources.  On  successful calls, fork returns zero to the
                     57: child and the process id of the child to the parent.
                     58: 
                     59: 
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                     63: 
                     64: COHERENT Lexicon                                           Page 1
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