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Tutorial8: Links / Process Management

45 bytes removed, 12:57, 25 February 2021
INVESTIGATION 2: MANAGING PROCESSES
# Issue the following Linux command: <span style="color:blue;font-family:courier;font-weight:bold">sleep 700</span><br><br>
# Notice that this process will run for '''700 seconds''', and is forcing the user to wait until this process finishes.<br>A process that is running in the terminal is referred to as a '''foreground process'''.<br><br>The Unix/Linux system is designed to allow users to send '''preemptive signals''' to manage those processes.<br><br>
# Press the key combination: <span style="color:blue;font-family:courier;font-weight:bold">&lt;ctrl&gt;&lt;-c&gt;</span><br><br>You should notice that the process that was running in the foreground has been '''interrupted''' (i.e. terminated). '''NOTE:''' The '''ctrl-c''' key combination sends '''SIGINT''' ('''Signal Interrupt''') to terminate a process that is running.<br><br>
# Reissue the Linux command: <span style="color:blue;font-family:courier;font-weight:bold">sleep 700</span><br><br>
# Press the key combination: <span style="color:blue;font-family:courier;font-weight:bold">&lt;ctrl&gt;&lt;-z&gt;</span><br><br>
# You should now see output similar to what is displayed below:<br><span style="font-family:courier;font-weight:bold">[1]+ Stopped sleep 700</span><br><br>'''NOTE:''' This indicates that this process has been placed into the '''background'''.<br>This is useful in order to "'''free-up'''" the terminal to run other commands.<br><br>
# Clear your bash shell terminal screen.<br><br>
# Issue the following Linux command: <span style="color:blue;font-family:courier;font-weight:bold">jobs</span><br><br>You should see the following output similar that was displayed above:<br><span style="font-family:courier;font-weight:bold">[1]+ sleep 700 &</span><br><br>This display indicates that this process in the background is '''running in the background'''<br>(denoted by the ampersand character "&"). Now the command is counting-down to zero.<br><br>
# Issue the following Linux command: <span style="color:blue;font-family:courier;font-weight:bold">fg</span><br><br>You should notice that the ''sleep'' command is now running in the '''foreground'''.<br><br>You can run commands with ampersand "'''&'''" to run processes in the background.<br><br>
# Press the key combination: <span style="color:blue;font-family:courier;font-weight:bold">&lt;ctrl&gt;&lt;-c&gt;</span> to '''terminate''' the process running in the foreground.<br><br>
# Issue the following Linux command: <span style="color:blue;font-family:courier;font-weight:bold">sleep 500 & sleep 600 & sleep 700 &</span><br><br>
# Issue the '''jobs''' command. What do you notice?<br><br>
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