No there is no space between * and .fastq.gz

Sorry I am new to R.

I ran ls -1 *.fastq.gz and got following output Error: object '.fastq.gz' not found

Then I ran ls -1 and got following output Error in ls - 1 : non-numeric argument to binary operator

Thank you for the reply. I will keep this in mind.

Although it is better to be safe than sorry, most likely one won't have problems with cat *.fastq.gz > File_Big.fastq.gz. Bash-related shells first parse the glob, only then they create the output file. A little test:

echo "1" > 1.txt
echo "a" > a.txt
cat *.txt > a1.txt
nl *.txt > a1_nl.txt

Now cat a1.txt shows:

1

a

And cat a1_n1.txt shows:

 1  1
 2  1
 3  a
 4  a

I performed the test above in bash and zsh, which I believe are the two most used shells currently.

C shells create the output file before parsing the glob, and indeed cat *.fastq.gz > File_Big.fastq.gz would cause a big problem, probably filling the disk.