Playing with sed ( stream editor )

---

echo "Greater than symbol puts the console output in a new file."
echo "Two greater than symbols puts the console output at the end of an existing file."
echo "Format of sed is s as a command forward slash to indicate a regular expression"
echo "and then the replacement in slashes."
echo "Line 1 ORIGINAL">text.txt
echo "Line 2 a. ORIGINAL b. original c. ORIGINAL">>text.txt
sed -i 's/ORIGINAL/SUBSTITUTE/' text.txt
cat text.txt
echo "Press enter to continue"
read Foo
sed -i 's/SUBSTITUTE/ORIGINAL/' text.txt
echo "Doing glogal replace ( multiple times on a line ) with g option."
sed -i 's/ORIGINAL/SUBSTITUTE/g' text.txt
cat text.txt
echo "sed is case sensitive"

---

At a console you can enter "man sed" without the quotes to see how the sed utility works. The option -i means to edit files in place and can be used to create a backup if needed. Many more useful options are available and this is just a simple example of the use of this utility. You can cut and paste this into a script as a demo to test it for yourself. It is easier for me to understand when I change things and see how they work. I changed this today to read "press enter" instead of "any key".