Aditinal information

tail -1000  < filename > > newfile


cat < filename > | grep -i " < Date format > "  > new filename


cat < filename > | grep -i " < Date format > "  >>  new filename ( append )

Searching for files for particualr time period: 

find . -mtime -5 -mtime +10 -exec rm {} \;

Here -mtime -days and -mtime +days means from -days till +days. 

This finds all the files in the current folder from last 5 days till last

10th day and executes rm command on all of them!

To combine several text files into a single file in Unix, use the cat command:

cat file1 file2 file3 > newfile  

Replace file1, file2, and file3 with the names of the files you wish to combine, in the order you want them to appear in the combined document. Replace newfile with a name for your newly combined single file.

If you want to add one or more files to an existing document, use the format:

cat file1 file2 file3 >> destfile

This command will add file1, file2, and file3 (in that order) to the end of destfile.

Note: If you use > instead of >>, you will overwrite destfile rather than add to it.