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Full Discussion: popen hangs program during cmd execution
Top Forums Programming popen hangs program during cmd execution Post 302388922 by Jess83 on Friday 22nd of January 2010 12:42:55 AM
Old 01-22-2010
popen hangs program during cmd execution
How can I get around this? when my program reaches the following popen job it halts the program until the ping/netstat/ipconfig/traceroute is completed then resume to the rest of the program...

Code:
FILE *in;
  extern FILE *popen();
  char buff[1024];
  char newline[100];
  char nstat[1024];
  char nping[1024];
  char tracert[2048];
  char iconfig[1024];
  strcpy(newline, "\r\n");  



  if (!(in = popen("ping -c 3 www.primus.ca ", "r"))) {
    exit(1);
  }
 
  
  while (fgets(buff, sizeof(buff), in) != NULL ) {
    strcat(nping, buff);
    }

  strcat(nping, newline); 
 

  pclose(in);

So I figured I could run the process with no hangup and in background so I went

Code:
popen("nohup ping -c 3 www.primus.ca &", "r")

It still halt the program until the ping is completed... the only difference im getting is in the meantime the program is halted I get

nohup: redirecting stderr to stdout
nohup: redirecting stderr to stdout
nohup: redirecting stderr to stdout
nohup: redirecting stderr to stdout
 

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LEARN ABOUT PLAN9

nohup

NOHUP(1)							   User Commands							  NOHUP(1)

NAME

       nohup - run a command immune to hangups, with output to a non-tty

SYNOPSIS

       nohup COMMAND [ARG]...
       nohup OPTION

DESCRIPTION

       Run COMMAND, ignoring hangup signals.

       --help display this help and exit

       --version
	      output version information and exit

       If  standard  input  is a terminal, redirect it from an unreadable file.  If standard output is a terminal, append output to 'nohup.out' if
       possible, '$HOME/nohup.out' otherwise.  If standard error is a terminal, redirect it to standard output.   To  save  output  to	FILE,  use
       'nohup COMMAND > FILE'.

       NOTE: your shell may have its own version of nohup, which usually supersedes the version described here.  Please refer to your shell's doc-
       umentation for details about the options it supports.

AUTHOR

       Written by Jim Meyering.

REPORTING BUGS

       GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
       Report nohup translation bugs to <http://translationproject.org/team/>

COPYRIGHT

       Copyright (C) 2017 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

       Full documentation at: <http://www.gnu.org/software/coreutils/nohup>
       or available locally via: info '(coreutils) nohup invocation'

GNU coreutils 8.28						   January 2018 							  NOHUP(1)
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