9 Limitations ¶

If the terminal hangs up and the buffer is modified and not empty, ed attempts to write the buffer to the file ed.hup or, if this fails, to $HOME/ed.hup.

If a text (non-binary) file is not terminated by a newline character, then ed appends one on reading/writing it. In the case of a binary file, ed does not append a newline on reading/writing. A binary file is one containing at least one ASCII NUL character. If the last line has been modified, reading an empty file, for example /dev/null, prior to writing prevents appending a newline to a binary file.

In order to keep track of the text lines in the buffer, ed uses a doubly linked list of structures containing the position and size of each line. This results in a per line overhead of 2 ‘pointer’s, 1 ‘long int’, and 1 ‘int’. The maximum line length is INT_MAX - 1 bytes. The maximum number of lines is INT_MAX - 2 lines.

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