Using the ed editor
The ed editor is a line editing program available in the shell for editing text files. When you edit a file with ed, the file is copied into the edit buffer, a temporary storage area. You use various subcommands to edit the text in the buffer. When you end your edit session, the contents of the buffer are written to the file system, overwriting the previous contents of the file.
With ed, you work with one line in the buffer at a time. In this discussion, that position in the buffer is called the current working line.
For more information, see the ed - Use the ed line-oriented text editor description in z/OS UNIX System Services Command Reference.