HCS Blog

There are time when you need to escape special characters in a bash script like dollar signs or backticks.  If you ever need to quote an entire section of text in a bash script without having to escape all special characters, use the cat command with EOF in single quotes.

When EOF is enclosed in single quotes, it ignores any special characters and will not interpret them in your script.  

The following command will print out the lines in between ‘EOF’ and EOF to the screen.


cat << 'EOF'

Lines with $signs are OK

Line with `backticks`

EOF


This is a handy command for your arsenal.  Enjoy.

sudo /usr/local/aw/start-server


sudo /usr/local/aw/stop-server

This command will replace the line that contains “This is a test” with “Is it Friday yet?” in the test.txt document.




sed -i "" '/This is a test/ c\

Is it Friday yet?\

' test.txt


Here is a breakdown of the above command.

The -i will edit the file in place.

The "" will get around not having an extension after the -i as required by os x.  

c\  is the change flag.  The above command is separated on multiple lines to make the c\ flag work properly.  If you try to enter the command on one line, it will fail because the c\ has issues with escaping the backslash.

You could also use sed -i.bak which would create a backup of the file before it’s edited instead of the "".

The remainder of the command:  replace the line that contains “This is a test” with “Is it Friday yet?” in the test.txt document.

This is a sed command to replace the word false with true in the updates.xml document.

sed -i "" 's/false/true/' /Users/work/Desktop/updates.xml 

Step 1.  Create a folder on the desktop called scripts.

Step 2.  Create a script named “postinstall” and put it in the scripts folder on the Desktop.  

NOTE:  do not add .sh to your script name or it will fail.  Best practice is to use a plain text editor when creating scripts.  IE.. TextWrangler or pico in the CLI.

Step 3.  Run the following command.  Enter your administrator password when prompted.

sudo pkgbuild --identifier com.mypackage.com --nopayload --scripts /Users/work/Desktop/scripts /Users/work/Desktop/MyPayFree.pkg

Step 4.  The package will be created and saved to your desktop.