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authorpriyanka2015-06-24 15:03:17 +0530
committerpriyanka2015-06-24 15:03:17 +0530
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+clear
+flag=1
+mode(-1)
+clc
+
+printf("Example 5 : Show the effect of creating an orphan by letting child sleep for 2 minutes where parent dies immediately \n")
+disp("****************************************************************")
+disp("Answer : ")
+disp("INSTRUCTIONS : ")
+halt(' ')
+disp("1.These programs are part of systems programming PURELY in Unix and the commands have NO EQUIVALENT IN SCILAB")
+halt(' ')
+disp("2.However the .c files which are displayed here are also made into a seperate file.If you are a unix user then try compiling and running the programme with gcc or cc compiler")
+halt(' ')
+disp("3.The outputs displayed here are just MOCK OUTPUTS which are DISPLAYED IN THE TEXTBOOK")
+halt(' ')
+disp("4.The inconvenience is regretted.")
+halt('.............Press [ENTER] to continue.....')
+halt("")
+clc
+printf("\tUNIX SHELL SIMULATOR(DEMO VERSION WITH PRELOADED COMMANDS)\n\n\n")
+i=0
+i=i+1;f(i)='/* Program: orphan.c -- Creates an orphan by letting child sleep for 2 minutes.'
+i=i+1;f(i)=' Parent doesn'+ascii(39)+'t call wait and dies immediately */'
+i=i+1;f(i)='#include <stdio.h>'
+i=i+1;f(i)='int main(void) {'
+i=i+1;f(i)=' int pid;'
+i=i+1;f(i)=' if ((pid = fork()) > 0) /* Parent */'
+i=i+1;f(i)=' exit(10); /* Parent exits without calling wait */'
+i=i+1;f(i)=' else if (pid == 0) { /* Child */'
+i=i+1;f(i)=' sleep(2); /* Lets parent die in this time frame */'
+i=i+1;f(i)=' printf('+ascii(34)+'CHILD: Adopted by init now, PPID: %d\n'+ascii(34)+',getppid());'
+i=i+1;f(i)=' exit(0);'
+i=i+1;f(i)='}'
+i=i+1;f(i)='}'
+n=i
+
+
+printf("\n\n$ cat orphan.c # to open the file emp.lst")
+halt(' ')
+u=mopen('orphan.c','wt')
+for i=1:n
+ mfprintf(u,"%s\n",f(i))
+ printf("%s\n",f(i))
+end
+mclose(u)
+halt('')
+clc
+
+halt(' ')
+ printf("$ cc orphan.c")
+ halt(' ')
+ printf("$ a.out ....no response for 2 seconds...")
+ halt(' ')
+ sleep(2000)
+ printf("CHILD: Adopted by init now, PPID: 1")
+ halt(' ')
+ printf("$ echo $?")
+ halt(' ')
+ printf("10")
+ halt(' ')
+
+printf("\n\n\n$ exit #To exit the current simulation terminal and return to Scilab console\n\n")
+halt("........# (hit [ENTER] for result)")
+//clc()
+
+printf("\n\n\t\t\tBACK TO SCILAB CONSOLE...\nLoading initial environment')
+sleep(1000)
+
+