56 lines
3.0 KiB
Plaintext
56 lines
3.0 KiB
Plaintext
This version of ed is not strictly POSIX compliant, as described in the
|
|
POSIX 1003.2 Draft 11.2 document (see the file `ed-1003.2'). BSD commands
|
|
have been implemented wherever they do not conflict with the POSIX
|
|
standard. In addtion, the POSIX rule that says a range of addresses
|
|
cannot be used where only a single address is expected has been relaxed
|
|
(see the file `legal-addrs').
|
|
|
|
The BSD which have been added include the BSD `W' command for appending
|
|
text to an existing file, the BSD `s' command (i.e., s[rgp]*) to repeat
|
|
a previous substitution, the BSD `z' command for scrolling through the
|
|
buffer, and the BSD `wq' command for exiting after write. The BSD line
|
|
addressing syntax (i.e., `^' and `%' - see the file `legal.addrs') is also
|
|
recognized.
|
|
|
|
The POSIX interactive global commands `G' and `V' are extended to support
|
|
multiple commands, including `a', `i' and `c'. The command format is the
|
|
same as for the global commands `g' and `v', i.e., one command per line
|
|
with each line, except for the last, ending in a backslash (\).
|
|
|
|
If crypt is available, files can be read and written using DES encryption.
|
|
The `x' command prompts the user to enter a key for encrypting/decrypting
|
|
subsequent reads and writes. If only a newline is entered as the key,
|
|
then encryption is disabled. Otherwise, a key is read with echoing turned
|
|
off until a newline is entered. For more information on the encryption
|
|
algorithm, see the bdes(1) man page. Encryption/decryption should be
|
|
fully compatible with SunOS DES.
|
|
|
|
An extension to the POSIX file commands `E', `e', `r', `W' and `w' is that
|
|
<file> arguments are processed for backslash (\) escapes, i.e., any
|
|
character preceded by a backslash is interpreted literally. A trailing
|
|
backslash is ignored. If the first unescaped character of a <file>
|
|
argument is a bang (!), then the rest of the line is interpreted as a
|
|
shell command and no escape processing is performed by ed. This rule does
|
|
not apply to the 'f' command (described below).
|
|
|
|
While the default file name cannot be set to a shell command (i.e.,
|
|
!<shell-cmd>) via any of the `r', `w', and `e' commands, POSIX evidently
|
|
does not preclude using the `f' command for this purpose. Upon reading
|
|
or writing the default file when its name begins with a bang (!), ed
|
|
interprets the rest of the line as a shell command and attempts to execute
|
|
it. Escape processing is not performed in this case. The `f' command
|
|
can be used in this way as a simple macro function. For example, after
|
|
setting the default file name to `!echo hello, world', the command `.r'
|
|
inserts the line `hello world' after the current line. The `f' command
|
|
with no arguments prints the default unescaped file name.
|
|
|
|
--
|
|
The following commands are neither part of POSIX 1003.2 D11/2 nor are
|
|
they supported in this version of ed.
|
|
|
|
The vi command: (addr1,addr2) !<shell-cmd> which replaces a range of
|
|
lines with the output of a shell command is not supported.
|
|
|
|
The vi command: [rwe] !!, where !! is replaced by the previous
|
|
!<shell-cmd> is not supported.
|