rewrite

#!/bin/bash
# script to collect input until the end then overwrite an existing file
# with the provided input. Intended to simplify this pattern:
# cat file | grep | awk | sed > temp
# rm file
# mv temp file
# into this pattern:
# cat file | grep | awk | sed | rewrite file

# need the file to overwrite
overwriteFile=$1

if [[ -z "$overwriteFile" ]]
then
  echo "must provide a file to rewrite"
  exit 1
fi

if [[ ! -f "$overwriteFile" ]]
then
  echo "$overwriteFile does not exist, either there's a typo or you're using the wrong command"
  exit 2
fi
tmpFile=$(mktemp /tmp/rewrite-script.XXXXXX)

cat > $tmpFile
rm $overwriteFile
mv $tmpFile $overwriteFile