Basic bash script question re: file size or # of lines in a file

the_fornicator · 09-03-2009, 08:46 AM

Hi there,

Sorry, sorta new to scripting. I tried doing a bunch of searches, but it's more of a syntax error. Hoping someone can help.

I'm trying to find either the number of lines in a file or the size of a file. Assuming both will yield the same result if it's empty or not -which is all I care about (i.e. if the file is empty)

My script looks like this:

#!/bin/bash

somefile="/home/dir/file.txt"

# do stuff to the file

filesize=$(awk 'END {print NR}' $somefile)
echo "The file size is $filesize"

---
But when I try to run the script, I'm getting a syntax error saying that the '(' is unexpected in the "filesize=$(awk 'END {print NR}' $somefile)" line.

Thoughts? Suggestion?

Thanks in advance!

theNbomr · 09-03-2009, 09:11 AM

Your script worked for me. Are you sure your shell is a genuine bash of recent vintage? If you replace the '$( .... )' notation with backticks, does it work?
--- rod.

the_fornicator · 09-03-2009, 09:14 AM

p.s I searched the forums some more and tried this:

#!/bin/bash

somefile="dir/file.txt"

filesize=$(stat -c%s $somefile)
echo "filesize is $filesize"

When executed, I get a, 'filesize=$' not expected.

Wondering what I'm doing wrong. Thanks in advance again.

the_fornicator · 09-03-2009, 09:21 AM

Quote:

Originally Posted by theNbomr

Your script worked for me. Are you sure your shell is a genuine bash of recent vintage? If you replace the '$( .... )' notation with backticks, does it work?
--- rod.

Do you mean like:
filesize=$(awk `END {print NR}` $somefile)

(I replaced the original ' with ` (backticks) and I'm still getting a 'filesize=$' not expected)

To answer your other question, I honestly couldn't tell you. I'm trying to throw something together on a work server so I don't know anything about it. Might be an environment variable... or something, but this stuff worked the other day.

I can run it in the command prompt no problems, if that's of any consolation.

the_fornicator · 09-03-2009, 09:31 AM

Quote:

Originally Posted by theNbomr

Your script worked for me. Are you sure your shell is a genuine bash of recent vintage? If you replace the '$( .... )' notation with backticks, does it work?
--- rod.

Wait.. I'm a tool.

I just understood what you were saying. i.e. I did this:

filesize=`awk 'END {print NR}' $somefile`

and that worked.

Care to educate a person as to why this is?

Tbanks for your help, btw.

colucix · 09-03-2009, 09:32 AM

Sorry... posted by mistake.

David the H. · 09-03-2009, 09:41 AM

theNbomr is talking about the old way to embed commands using ` backticks instead of $(), not changing the single quotes, which in this case protect the expression that's being passed to awk.

Code:

filesize=`awk 'END {print NR}' $somefile`

This shouldn't be your problem though, unless your version of bash is incredibly old (run 'bash --version' to find out).

You should probably also use double-quotes around the string when setting variables, to ensure that the output is seen as a single string and to escape any bad substitutions. Not that that's necessarily the problem here, however.

Code:

filesize="$(awk 'END {print NR}' $somefile)"

But if all you want to do is determine if the file is empty, there are already tests available for that.

Code:

if [[ -f "$1" && ! -s "$1" ]]; then
        echo "Regular file $1 is an empty file."
elif [[ -f "$1" && -s "$1" ]]; then
        echo "Regular file $1 is not empty."
else
        echo "$1 is not a regular file."
fi

Edit: I see you figured the backquote thing out on your own.

I don't know why the original code isn't working for you. It works for me with no problem. Is there anything unusual about your setup that we should know about?