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sh / diff syntax trouble

i can get my command to run from the command line, but it breaks when i put it in an sh if loop

from the command line

Code:

md5 -q /file | diff --brief /file.md5 -

(the "-" is supposed to take input from stdin)

in the script i have this

Code:

if [[ md5 -q $LOG | diff --brief $SUM - ]]; then

    echo;echo "They are new!";echo

else

    echo;echo "do nothing.";echo

fi

but this is the output that i get:

Code:

[[: not found

diff: extra operand

diff: Try `diff --help' for more information.



do nothing.

well that's just not right in any way.. did you read any scripting howto's, like the bash advanced scripting howto at tldp.org? firstly [[ is not a command, the synonym for test is just [ closed with ] also wrap the string there inside the test with $(md5...SUM -) as that also totally breaks the syntax:

if [ $(md5 -q $LOG | diff --brief $SUM -) ];

no idea if what you're actually trying to evaulte will make sense within the context of a test statement though.