Hi all,

I'm brand new to the forums here at LQ, hope I'm posting to the right place.

I am writing a command menu program and cannot figure out the correct way to add my command into a loop. I want the prompt to continue popping up as long as the output of grep = 0, so I understand the need for a while or until loop. However, I cannot get my command to be in the loop, so $? is still reading as 0 because it's outside the loop.

When I run it the first time, it doesn't let my executable file open in vi. However, after adding a text file name the second time, it still won't open in vi and keeps prompting me. I know that this is because my command is not in the loop, but as I said, I can't figure out how to put it.

file $editfile | grep -qw "executable"

while [ "$?" = "0" ]
do
echo -e "\n"
echo -e "\t THIS IS A BINARY FILE - TRY AGAIN\n"
read -p " Please Enter File To Be Edited: " editfile
done

Any help would be greatly appreciated!

I was finally able to figure it out by adding the command to the end of the loop as well...

So instead of

file $editfile | grep -qw "executable"

while [ "$?" = "0" ]
do
echo -e "\n"
echo -e "\t THIS IS A BINARY FILE - TRY AGAIN\n"
read -p " Please Enter File To Be Edited: " editfile
done


IT BECAME:


file $editfile | grep -qw "executable"

while [ "$?" = "0" ]
do
echo -e "\n"
echo -e "\t THIS IS A BINARY FILE - TRY AGAIN\n"
read -p " Please Enter File To Be Edited: " edit file
file $editfile | grep -qw "executable"
done


Thought that I'd share my find in case it helps others in the future.

probably you only mistyped, but edit file and editfile are two different things, do not mix them.
Also you may need to check if $editfile exists (see man test for example).
also remember for example pictures are not executables but still cannot be edited as a text file.

1 members found this post helpful.

Welcome to LinuxQuestions

In addition, not all executable files are binary.

2 members found this post helpful.

Here is an menu example that you may be able to modify to meet your needs:

Thank you guys for the help!

The binary exclusion is what I've been having the most trouble with. When using file command, I was trying to find what identifying symbols or words are used to exclude binary files. Thank you for the reminder that executables are still text that can be edited, such as my menu_script.sh file that this particular line of code comes from.

Would changing the command to:

file -i $editfile | grep -qw "text"

if [ "$?" = "1" ]
then
echo "This is a binary file"

work better? It is searching specifically looking for text files, not executable (which is ok to edit in vi)

Thanks!

You open a binary in vi, I think you'll know it.

Lol I just meant to grep out anything that specifically makes a file binary. I know the binary file is full of non-human readable characters, but I wasn't sure if using the file command would give insight to the file being binary.

There are usually many ways to accomplish the same task so if it works for you then yes.

to compare numbers you ought to use -eq, -lt or -gt instead of =

Just because a file is not text does not necessarily make it binary.

Also, if and while evaluate the return value, currently you are evaluating the return value from [] (which I would recommend using [[]] instead), when in fact you could simply test
the return value of your command expression:

Yes it does. Well okay, it depends on your definition of "binary". For instance, another possible definition is that all files are binary, including text files.

+1