Grep for empty file

plawr · #1 (**permalink**) 10-01-2009

I have a program that takes a file in which I use a sed to remove some data that is not needed. If all of the data is removed. I want to grep for that in the file and print that there is no data left in the file. When I use sed, I replace a word with nothing but it still seems to leave a return carriage. Please give me some ideas on how to do this. Thanks!

Smiling Dragon · #2 (**permalink**) 10-01-2009

Code:

if egrep . file > /dev/null
then
    # File is not empty
else
    # File is empty (except for line feeds)
fi

Scrutinizer · #3 (**permalink**) 10-02-2009

Code:

if [ -s file ]; then
  echo not empty
else
  echo empty
fi

ripat · #4 (**permalink**) 10-02-2009

Quote:

Originally Posted by Scrutinizer

Code:

if [ -s file ]; then
  echo not empty
else
  echo empty
fi

The OP says that sed leaves a \n in the "empty file". So its size will be 1 byte and your test will show not empty.

You could also use the stat command:

Code:

if [[ $(stat -c %s file) == 1 ]];then echo "kind of empty";fi

cfajohnson · #5 (**permalink**) 10-02-2009

Quote:

Originally Posted by ripat

The OP says that sed leaves a \n in the "empty file". So its size will be 1 byte and your test will show not empty.

You could also use the stat command:

Code:

if [[ $(stat -c %s file) == 1 ]];then echo "kind of empty";fi

The stat command is not standard, and there are different versions:
Code:
$ stat -c %s .bashrc 
stat: illegal option -- c
usage: stat [-FlLnqrsx] [-f format] [-t timefmt] [file ...]

---------- Post updated at 06:49 PM ---------- Previous update was at 06:48 PM ----------

Quote:

Originally Posted by plawr

I have a program that takes a file in which I use a sed to remove some data that is not needed. If all of the data is removed. I want to grep for that in the file and print that there is no data left in the file. When I use sed, I replace a word with nothing but it still seems to leave a return carriage. Please give me some ideas on how to do this. Thanks!

Fix the sed command to delete the line instead of just the word.

Scrutinizer · #6 (**permalink**) 10-02-2009

OK, I see.
-deleted-

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