UNIX for Dummies Questions & Answers

I am going to build some commands/functions for common tasks that I have to perform (things like searching a filesystem for a certain string in a file).

I intend to write these as unix scripts. Then adding the location of these to my path.

How can I ensure that the variables specified when I use the commands are applied to the script.

For example.

I will write a command called grepall - which will search the entire file system from a specified point - returning the filename of files containing the specifed string....

The syntax from the command line would be similar to this....(don't worry if it's not right - just for arguements sake)

find /from/here -type f -print | xargs grep -l "mystring" 2>/dev/null


How do I construct the command to take in the arguements of (starting location) and (mystring) - so that I could just type

grepall /home/dir "hello"

Presumable something like

find $x -type f -print | xargs grep -l $y 2>/dev/null....... but then how do I make the function read in $x and $y from the command line entry?

I am using bash..... on solaris.

Here's one way to go:

#this will make sure only two parameters are being passed from the command line
if [ $# -ne 2 ]
then
echo "Usage: grepall [dir] [string]"
exit
fi

#this line will use the two arguments from the command line
find $1 -type f -print |xargs grep -l "$2" 2>/dev/null

I can't promise this will work, since I don't have access to a machine running solaris to test, but hopefully this stuff is the same across different unix flavors.

So you basically $1, $2, $3 ....etc will be the variables for every entry on the command line after the command itself..... that simple huh? No assignment requried?

You don't HAVE to assign the arguements that are passed from the comamnd line, but you can.

Did you get a chance to test out the above syntax to see if it worked in your environment?

Yeah - she's all good...thanks for that. Just needed to understand that the arguements can just be 'grabbed' from the command line with $1, $2 ......

The functions work great!

Here's something else to think about for this situation. Take the example usage syntax below:

grepall -d[dir] -s[string]

If you wanted to invoke your script as shown above, it is made possible by a shell command called getopts. I don't use it much, but I have seen it used by co-workers.

Here's a link if you're interested:
http://linuxdoc.org/LDP/abs/html/internal.html#EX33
Example 11-13.

I would prefer something which "thekid" has suggested, cause that gives the user to give the options any way he needs ... either <expression> <filename> or <filename> <expression>. It would be also a good coding practice to use swtich (-f, is) etc in your program...
Just an advice..

And ys if you intend to use $x and $y... you could do
$x=$1
$y=$2

As you have already figured out, All the arguments are stored in the series $1 $2 $3 ...

Thanks