Using variable with sed in Shell Script

Question

I'm writing a shell script to edit Change-Set attributes of aegis. The command I'm using is:

aegis -Change_Attributes -Edit

which opens up a vi editor to carry out the changes. I want to do a search and replace:

s/brief_description \= \"none\"\;/brief_description \=

\"test\"/g

Can I pass these directly to the open vi instance via the script without typing in any of it? I want to save the document (:wq) after editing it.

P.S. The file is a temporary file created when executing the command so I don't know the original path

Edit: I could used sed in this case:

sed -e 's/brief_description\ \=\ \"none\"\;/brief_description\ \=\

\"test\"\;/g'

The solution (inelegant hack??) would be to "cat" the output from aegis (setenv VISUAL cat), modify the out put stream with the above command and save it to a temp file, and use :

aegis -change_attributes -file <temp file>

EDIT2: I've almost got it to work. But there's a problem with the way I use "sed"

I have the following line in my script:

sed -i 's/brief_description\ \=\ \"none\"\;/brief_description\ \=\ \"${DESC}\"\;/g' temp_next.txt

But the $DESC variable does not evaluate to its value and the out put is given as:

brief_description = "${DESC}";

How can I pass DESC to sed that it would evaluate to it's actual value?

EDIT3:

Using

sed -i 's%brief_description\ \=\ \"none\"\;%brief_description\ \=\ \"'"$DESC"'\"\;%g' temp_next.txt

worked. I replace the normal delimiter (/) with % and put the environment variable in double quotes.

Answer 1

You don't need to know the path - the aegis app will supply that. You need to change the environment variable that specifies what editor aegis uses to point at a script, and in that script use the sed stream editor to perform your edits.

Edit: Regarding your variable name expansion problem, change the set of single quotes enclosing the whole sed substitution expression to double quotes. Variable substitution is turned off by single quotes.

Answer 2

I don't think that vanilla vi will do this, although vim might be able to this under control of a custom .vimrc. A better way would be to do the changes with sed and then open vi on the result.

Answer 3

If you pass the desired command in via the -c option then vi will execute the command immediately after starting the edit session, e.g.

vi -c 's/brief_description \= \"none\"\;/brief_description \= \"test\"/g' my_file

Oops. I forgot to say that the command is interpreted as an "ex" command, i.e. at the colon, so the command you've provided should work.

HTH

cheers,