Question

Since Solaris grep by default doesn’t have the -E option, I would have to update my bash to work with a specific grep. This is what I do.

It works on the command line, but when I put it in the bash file, it looks like the script doesn’t pick it up and still uses the normal grep. (I do not want to change the whole $PATH.)

Please advise:

export isSolaris=`uname -a | grep -i "sunos"`
if  [ -n "$isSolaris" ]; then
        alias grep="/usr/xpg4/bin/grep -E";
fi

Answer 1

bash and ksh don’t process aliases defined in a file until after the file is read… which means you can’t define it in the same script that will use it. You can put it in another file and . (source) that into your script, though.

Alternately, use a shell function.

mygrep() {
  if test -n "$isSolaris"; then
    /usr/xpg4/bin/grep -E ${1+"$@"}
  else
    grep ${1+"$@"}
  fi
}