NAME
edinplace - edit a file in place
SYNOPSIS
edinplace [--error=code] [[--file=file] command [arg ...]]
DESCRIPTION
edinplace runs command with its input from file (or standard input by
default), and then replaces the contents of file with the output of
command. To the extent possible, edinplace attempts to exit with the
same status as command.
If edinplace is run on standard input (no --file option), it must
inherit a file descriptor 0 that is open for both reading and writing.
When processing standard input, if edinplace does not encounter a fatal
error, it rewinds its standard input to offset 0 before exiting. Thus,
a script can first run edinplace command, then run another filter
command such as grep, and the resulting output will be the output of
grep on command’s output.
If no command is specified, edinplace just rewinds its standard input
to file offset 0. In this case, it is an error to supply the --file
option. Of course, rewinding only works when standard input is a real
file (as opposed to a pipe or device).
There are two options:
--error=code (-x code)
Ordinarily, edinplace attempts to exit with the same status as
command. However, if edinplace encounters some fatal error (such
as being unable to execute command), it will exit with status code.
The default value is 1. The range of valid exit codes is 1-255,
inclusive.
--file=file (-f file)
Specifies that file should be edited. Otherwise, edinplace will
edit its standard input (which must be opened for both reading and
writing).
--skipfrom
Skip the first line of the file if it starts "From ". If edinplace
is run without a command, positions the file offset at the start of
the second line of the file. If edinplace is run with a command,
then the first line of the file is neither fed to the command, nor
overwritten. This option is useful for running edinplace over mail
files, which sometimes start with a "From " line specifying the
envelope sender of the message. Since "From " is not part of the
message header, just a Unix convention, some programs are confused
by the presence of that line. Note that if you specify a command,
then edinplace resets the file offset to 0 upon exiting, even if
the --skipfrom option was present.
EXAMPLES
The following command prepends the string "ORIGINAL: " to the beginning
of each line in text file message:
edinplace -f message sed -e ’s/^/ORIGINAL: /’
The following command runs the spamassassin mail filter program on a
mail message stored in file message, replacing the contents of message
with spamassassin’s annotated output, and exiting with code 100 if
spamassassin thinks the message is spam. If edinplace encounters any
fatal errors, it will exit with code 111.
edinplace -x 111 -f message spamassassin -e 100
(spamassassin reads a mail message on standard input and outputs an
annotated copy of the message including information about whether or
not the message is likely to be spam and why. The -e option to
spamassassin specifies what exit status spamassassin should use if the
message appears to be spam; edinplace will use the same exit code as
the program it has run.)
To run spamassassin on incoming mail before accepting the mail from the
remote client, place the following line in an appropriate Mail Avenger
rcpt file as the last command executed:
bodytest edinplace -x 111 spamassassin -e 100
SEE ALSO
avenger(1)
The Mail Avenger home page: <http://www.mailavenger.org/>.
BUGS
edinplace does not make a copy of the file being edited, but rather
overwrites the file as it is being processed. At any point where
command has produced more output than it has consumed input from the
file, edinplace buffers the difference in memory. Thus, a command that
outputs large amounts of data before reading the input file can run
edinplace out of memory. (A program that outputs data as it reads even
a very large file should be fine, however.)
If command crashes or malfunctions for any reason, you will likely lose
the input file, since edinplace will view this as a program that simply
outputs the empty file.
AUTHOR
David Mazieres