#cat file01
The first meeting of the Linux System
Administrator's group will be held on Tuesday.
Another line
And here we have: System Administrator's Group as well.
1.System Administrator's group.
2.System Administrators Group.
3.System Administrators Group.
The first meeting of the Linux System
Administrator's group will be held on Tuesday.
System Administrators Group.

# sed '
>N
>s/SystemnAdministrator/DesktopnUser/
>s/System Administrator/Desktop User/
> ' file01
The first meeting of the Linux Desktop
User's group will be held on Tuesday.
Another line
And here we have: Desktop User's Group as well.
1.Desktop User's group.
2.System Administrators Group.
3.Desktop Users Group.
The first meeting of the Linux System
Administrator's group will be held on Tuesday.
Desktop Users Group.

# sed '
> s/System Adminitrator/Desktop User/
> N
> s/SystemnAdministrator/DesktopnUser/
> ' file01
The first meeting of the Linux Desktop
User's group will be held on Tuesday.
Another line
And here we have: System Administrator's Group as well.
1.Desktop User's group.
2.System Administrators Group.
3.Desktop Users Group.
The first meeting of the Linux System
Administrator's group will be held on Tuesday.
System Administrators Group.