bash

noir911 · 08-13-2008, 01:20 AM

I have written a script that checks size of a file - if size is greater that
zero, it sends out an email with the content of the file. I want to add
another file to the script and wondering if it is possible. Here is my script

Code:

#!/bin/bash
FILE="/path/to/file1"
LS="`ls -al $FILE | awk '{print $5}'`"
if [ $LS = "0" ]; then
       exit 1;
       else
  cat $FILE | /mail -s "Subject" joe@domain.com
fi

I have added /path/to/file2 to the FILE variable, like, FILE="/path/to/file1" && "/path/to/file2" - but it says permission denied on file2.

Is there any way to add file2 to the FILE variable?

Thanks for any help.

matthewg42 · 08-13-2008, 02:04 AM

In bash you have a test specifically to see if a file exists and has a size greater than 0 bytes: -s. There is no need to call ls and then awk to extract the size.

Here's how to do that:

Code:

#!/bin/bash

FILE=/path/to/a/file
if [ -s "$FILE" ]; then
    cat $FILE | mail ...
fi

Incidentally, you don't have to use the if ... then ... fi construct for this, it's much more compact and pretty to do it like this:

Code:

#!/bin//bash
FILE=/path/to/a/file
[ -s "$FILE" ] && cat "$FILE" | mail ...

Which style you use is a matter of taste really.

If you want to check multiple files, doing the same action on each, and do not much feel like copy-pasting the whole statement, you can use a function which takes a file name as an argument, and performs the test and mail action. Once you've written the function, you can call it with as many file names as you like:

Code:

#!/bin/bash

mail_if_non_zero_size () {
    [ -s "$1" ] && cat "$1" | mail ...
}

mail_if_non_zero_size "/path/to/some/file"
mail_if_non_zero_size "/path/to/a/second/file"
mail_if_non_zero_size "/path/to/yet/another/file"

The thing to know is that within a shell function, arguments which are passed when the function is called get assigned to the variables 1, 2, 3, 4, ... so you can take their value with $1, $2, $3, $4, ...

The -s test is one of many file-related tests. See the "CONDITIONAL EXPRESSIONS" section of the bash manual page for a full list.

theYinYeti · 08-13-2008, 02:11 AM

You could do it differently:

Code:

#!/bin/bash
FILES=(
  "/path/to/file1"
  "/path/to/file2"
  …
  "/path/to/fileN"
)
find "${FILES[@]}" -maxdepth 0 -type f ! -empty -print | while read f; do
  cat "$f" | /mail -s "Subject" joe@domain.com
done

Yves.

kenoshi · 08-13-2008, 02:11 PM

matthewg42 and Theyinyeti are doing a great job explaining how you can do this differently...so I'll focus on your original question.

Quote:

I have added /path/to/file2 to the FILE variable, like, FILE="/path/to/file1" && "/path/to/file2" - but it says permission denied on file2.

What happened here is because FILE="/path/to/file1" was assigned successfully to FILE, therefore /path/to/file2 was executed. However, file2 probably didn't have execute rights, so you got the permission denied error.

In other words, you tried to "run" /path/to/file2, when all you want to do was append the text "/path/to/file2" to "/path/to/file1"

If you wanted to append to an existing variable, easiest way is:

FILE="$FILE /path/to/file2"

Hope this helps.

matthewg42 · 08-13-2008, 02:15 PM

Having multiple file names in a single string value with whitespace separation is not a good idea - what happens when you get a filename with a space in it? It breaks. The reason I suggested an alternative is because the way you seem to want to do it is not robust.