You can use these commands:

```cat sequences.fa | perl -pe 's/>(.*)/>\1\t/g' | perl -pe 's/\n//g' | perl -pe 's/>/\n>/g' | grep -E -v '^$'
```

Explanation:

0. View your FASTA file
1. Append a tab to every header line
2. Join all lines
3. Split the single obtained line by the '>' character
4. Remove the empty line (the first line is empty due to the fact that '>' is the first character of the FASTA file)