Need help with C Shell pattern matching

[akvino]

Hello all. I am trying to write a script in C shell, that would check for the current directory and based on which directory it is, allow or dissalow 'rm' command.

My biggest problem so far is checking if the directory "pwd" is resstricted or not. Here is my code where I do pattern matching:


set localdir=`pwd`;
echo "$localdir" ;

if ("$localdir" == '/root') then
echo "this is your root directory";
exit
end if


if ( "$localdir" =~ *[go] ) then
echo "You are not allowed 1 delete files in $localdir!";
exit

else if ( "$localdir" =~ *[qff] ) then
echo "You are not allowed 2 delete files in $localdir!";
exit

else if ( "$localdir" =~ *[fone] ) then
echo "You are not allowed 3 delete files in $localdir!";
exit

endif



-----------------------
ANy of the named directories could have different path - for instance:

path1/go
path2/go
path3/go
etc...

What I have noticed, when I add data directory - it also dissalows root directory so the code:
if ( "$localdir" =~ *[data] ) then
echo "You are not allowed 3 delete files in $localdir!";
exit

endif

IS THE SAME AS:
if ( "$localdir" =~ *[root] ) then
echo "You are not allowed 3 delete files in $localdir!";
exit

endif

---------------------------------------



My question - what is the better way to implement pattern matching into this code? How does C shell interpret these pattern matching conditional statments (does it first convert them to binary?)

[lloyd_b]

You are misunderstanding exactly what the brackets ("[]") do.

The [] tells it "if the string matches *any* of these characters. So your "*[data]" would translate as "match if string is anything ending in "d", "a", "t", or "a". So "root" would match, as would "data", "ford", etc.

If you want to see if the end of the string matches "data", then the correct test would be:
if ( "$localdir" =~ *"data" ) then

As a better way to implement these, I'd suggest a "switch" data structure:
#!/bin/csh

set localdir=`pwd`;
echo "$localdir" ;

switch ("$localdir")
case "/root"
echo "This is your root directory"
exit
breaksw
case *"/go"
echo "You are not allowed 1 delete files in $localdir"
exit
breaksw
case *"/qff"
echo "You are not allowed 2 delete files in $localdir"
exit
breaksw
case *"/fone"
echo "You are not allowed 3 delete files in $localdir"
exit
breaksw
case *"/data"
echo "You are not allowed 4 delete files in $localdir"
exit
breaksw
endsw

Lloyd B.

[akvino]

You are misunderstanding exactly what the brackets ("[]") do.

The [] tells it "if the string matches *any* of these characters. So your "*[data]" would translate as "match if string is anything ending in "d", "a", "t", or "a". So "root" would match, as would "data", "ford", etc.

If you want to see if the end of the string matches "data", then the correct test would be:
if ( "$localdir" =~ *"data" ) then

As a better way to implement these, I'd suggest a "switch" data structure:
#!/bin/csh

set localdir=`pwd`;
echo "$localdir" ;

switch ("$localdir")
case "/root"
echo "This is your root directory"
exit
breaksw
case *"/go"
echo "You are not allowed 1 delete files in $localdir"
exit
breaksw
case *"/qff"
echo "You are not allowed 2 delete files in $localdir"
exit
breaksw
case *"/fone"
echo "You are not allowed 3 delete files in $localdir"
exit
breaksw
case *"/data"
echo "You are not allowed 4 delete files in $localdir"
exit
breaksw
endsw

Lloyd B.

Super - this is exactly what I needed. Thanks a bunch Lloyd.;)