rsync -av dir1 user@server1.cyberciti.biz:/path/to/dir1

OR

cp -av file1*.txt file2*.txt /path/to/dest

I need to correct those command as follows:

rsync -av dir5 user@server1.cyberciti.biz:/path/to/dir1
cp -av delta1*.txt delta2*.txt /path/to/dest

How do I replace dir1 with dir5 or file with delta and repeat the last command under bash shell?

The bash shell supports both history search and replace operations. The bash (and many other modern) shell provides access to the command history, the list of commands previously typed. The bash shell supports a history expansion feature found in other shell such as csh.

Syntax: Bash history search and replace the command args

The syntax is as follows for quick substitution and repeat the last command, replacing word1 with word2:

^WORD1^WORD2^

OR

!!:s/WORD1/WORD2

OR

!!:gs/WORD1/WORD2

In this example, I’m trying to copy a file called youtube-demo-andriod-app-part1.avi to /backup directory
$ cp youtube-demo-andriod-app-part-102.avi /backup/
To repeat the last command with a substitution:
$ ^102^1002^
OR
$ !!:s/102/1002
Sample outputs:

cp youtube-demo-andriod-app-part-1002.avi /backup/

Please note that this substitutes only applies to the first occurrence. For example:
$ cp -av file1*.txt file2*.txt /path/to/dest
Replace file1 and file2 with delta1 and delta2, enter:
!!:gs/file/delta
Sample outputs:

cp -av delta1*.txt delta2*.txt /path/to/dest

You can also repeat the previous substitution with &:
cp -av file1*.txt file2*.txt /path/to/dest
!!:gs/file/delta-&/
Sample outputs:

cp -av delta-file1*.txt delta-file2*.txt /path/to/dest