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Tutorial5: Redirection

20 bytes added, 12:21, 3 February 2021
INVESTIGATION 1: BASICS OF REDIRECTION
# Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">ls -l > listing.txt</span><br><br>What information does the '''listing.txt''' file contain?<br><br>
# Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">pwd > listing.txt</span><br><br>What happenned to the original contents of the file called '''listing.txt'''? Why?<br><br>
# Issue the following Linux command (use 2 greater-than signs): <span style="color:blue;font-weight:bold;font-family:courier;">date >> listing.txt</span><br><br>What information does the '''listing.txt''' file contain? Why?<br><br># Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cat listing.txt cars > combined.txt</span><br><br>What information does the '''combined.txt''' file contain? Why?<br><br>'''NOTE''': The '''cat''' command stands for "'''concatenate'''" which means to '''combine''' contents of multiple files into a single file.<br>This is why the command is called "''cat''".<br><br># Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cat listing.txt cars murray 2> result.txt</span><br><br>What is displayed on the monitor? What information does the '''result.txt''' file contain? Why?<br><br>
# Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cat listing.txt cars murray > myoutput.txt 2> /dev/null</span><br><br>What is displayed on the monitor? What happened to the error message?<br><br>
# Issue the following Linux command: <span style="color:blue;font-weight:bold;font-family:courier;">cat listing.txt cars murray > myoutput.txt 2> result.txt</span><br><br>What is displayed on the monitor? what do those files contain? Why?<br><br>The '''Here Document''' allows you to redirect stdin from with the Linux command itself. Let's get some practice using the Here Document.<br><br>
# Issue the following Linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">cat <<+<br>line 1<br>line 2<br>line 3<br>+</span><br><br>What do you notice?<br><br>
# Issue the following Linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">grep 2 <<+<br>line 1<br>line 2<br>line 3<br>+</span><br><br>What do you notice? How does this differ from the previous command? Why?<br><br>
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