a begginers question

hadar · #1 (**permalink**) 01-06-2008

hey
i'm very much new to unix
i'm trying to write a script which goes through given files and checks if the files begin with # and if they are executable
my problem is that when i try to check the result of my query i'm getting nada
let me explain :
when i write
if (`file $i | grep 'executable' `=~ ?*)

or
if (`head -1 $i | grep '^#' ` != ``)

i'm getting weird results
i'm guessing my sintax is way off here...
any suggestions on the proper syntax for checking if the return value of this query isn't NULL...?

thanks in advance

porter · #2 (**permalink**) 01-06-2008

You could

(a) check if executable by "test -x filename"

(b) get the very first character using "dd if=filename bs=1 count=1"

hadar · #3 (**permalink**) 01-06-2008

sorry for being such a pain,
but i'm supposed to specificly check that the outcome "file filename"
has the word executable in it...
and i didn't quite get the (b) part -
should i use it as a condition like so:

if ("dd if=file name bs = 1....." == "#")

(as i said...very new to unix

)

porter · #4 (**permalink**) 01-06-2008

Quote:

Originally Posted by hadar

but i'm supposed to specificly check that the outcome "file filename" has the word executable in it...

Who says?

Code:

if test -x $FILE
then
    FIRSTCHARS=`dd if=$FILE bs=1 count=2`
    if test "$FIRSTCHARS" = "#!"
    then
          echo starts with "$FIRSTCHARS"
    fi
fi

Code:

file $FILENAME | grep executable >/dev/null
if test "$?" = "0"
then
     echo file says its executable
fi

hadar · #5 (**permalink**) 01-06-2008

thank you very much, now it's all very clear

frank_rizzo · #6 (**permalink**) 01-06-2008

Quote:

Originally Posted by porter

Who says?

I bet his teacher says...

fyi to the poster begginer is really spelled as beginner

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