How can I check if a file exists in shell script. Basically, I want to check if a file Test_msgs has been created today. If it has been then append data to it. Otherwise, create it. I have written the following but it does not work.

todaysdate=$(date +%d%m%Y)
timenow=$(date +%H%M%S)
checktestfile='Test_msgs_$todaysdate_*.txt'
testfile='Test_msgs_'$todaysdate'_'$timenow'.txt'

if [ -f checkTestfile ]; then
echo "File appended to" >> testfile
else
echo "File created" > testfile
fi

Just a silly error; you forgot a "$" before "checkTestfile" inside the -f test. You also mis-capitalized "checkTestfile"; it should be "checktestfile" to match the variable declaration above it.

You used the -f, but there are a couple of others also that may be of interest.

if [ -r $checktestfile ] ==> to see if you can read it (may not have access)
if [ -s $checktestfile ] ==> to see if the file is non-zero or not empty

Also, in your scripting, you set a variable
But you access it as in -- need the $ before variable

@gugs:

there is no need for an if condition. You may directly use >> as it will append if file exists, or will create file if it does not exist.

True, but he wanted the first message in the file to be different based on whether it was created or appended-to. That then requires a test.