A "counter" in Linux

[bdlbfrb08]

I am trying to count the # of a files with a certain pattern in a directory. This is what I have written. The shell is bash.

function counter(){
z=0;
for i in $( ls | grep "$pattern*" ); do
z = `expr $z + 1`
done
if test `expr $z` -lt 10
then echo v0$z
else
echo v$z
fi
}

My error is "bash: z: command not found" I have been messing with all sorts of specifications of the for loop, and I can't seem to make it work. Help anyone?

The last if statement is just more of a formatting thing than anything else.

(I only started even touching linux like a month ago, so I know there is probably a much better way to do this)

[wje_lf]

My error is "bash: z: command not found"

Instead of saying this:

z = `expr $z + 1`

say this:

z=`expr $z + 1`

Hope this helps.

[bdlbfrb08]

It worked. Thank you!

[secondmouse]

Using ls to count files is not reliable. For example, create these two files under a folder:
touch hello "hello world"
then run your code


z=0
PATTERN="hello*"
for i in $( ls | grep "$PATTERN" ); do z=`expr $z + 1`; done
echo $z

you get 3 instead of 2 as a result

I would use command find combined with wc instead, like this:
PATTERN="hello*"
find . -name "$PATTERN" | wc -l

[bdlbfrb08]

Thank you for your suggestion. I am not sure it is necessary, but I implemented it, my pattern is very distinctive, and it is good programming practice.

Also good to know for future reference. Thank you.

[i92guboj]

Using ls to count files is not reliable. For example, create these two files under a folder:
touch hello "hello world"
then run your code


z=0
PATTERN="hello*"
for i in $( ls | grep "$PATTERN" ); do z=`expr $z + 1`; done
echo $z

you get 3 instead of 2 as a result

I would use command find combined with wc instead, like this:
PATTERN="hello*"
find . -name "$PATTERN" | wc -l

In fact, and since he explictly said he uses bash, there's not even need for find (as long as he don't need to recurse subdirs), just use

z=0; for i in ${PATTERN}; do z=$((z+1)); done;

But yeah, if you prefer to use find, it's smarted to use wc -l as you said, instead of a loop.

OSS goodnes, zillions of ways to accomplish a given goal.

[secondmouse]

You can use option -maxdepth 1 in command find to disable the recursive feature.
PATTERN="hello*"
find . -maxdepth 1 -name "$PATTERN" | wc -l