sed命令在bash脚本中引发错误

Question

I have a simple Bash shell Script to loop through each file in a directory and check is the copyright message is at the top of the file. If it's not there is should add it.

The script is giving an error when I try to use a variable in the sed command. I have looked at other similar questions and tried double quotes "", I have tried using a different operator but still can't find the solution. Can someone possibly point out what I am doing wrong?

Msg='/*------------------------------------------------------------------------------
*******************************************************************************
* Copyright message here
*******************************************************************************
*----------------------------------------------------------------------------*/'

for file in * 
  do
    if grep -Fxq "$Msg" $file
      then
        echo Marvel Message already exist: $file
    else
      if test -f "$file" 
        then
         echo "Adding Message to file: $file"
         sed -i "1s/^/${Msg}\n/" $file
      fi
    fi
done

Answer 1

I would not use sed for this. I would use ed:

ed "$file" <<END
1i
$Msg
.
wq
END

Or, using sponge from the moreutils package

{ echo "$Msg"; cat "$file"; } | sponge "$file"

Answer 2

Simply you can do it with marge like this, here with echo "$Msg" > tmp.txt you are creating a file with your $Msg as header of the tmp file. And with cat $file >> tmp.txt you are merging the file.

for file in * 
do
if grep -Fxq "$Msg" "$file"
  then
    echo Marvel Message already exist: "$file"
else
  if test -f "$file" 
    then
     echo "Adding Message to file: $file"
     #sed -i "1s/^/${Msg}\n/" $file
     echo "$Msg" > tmp.txt
     cat "$file" >> tmp.txt
     mv tmp.txt "$file"
   fi
 fi
done

Hope this will help you.