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.TH PIPEFILE 1

.SH NAME

pipefile \- attach filter to file in name space

.SH SYNOPSIS

.B pipefile

[

.B -d

] [

.B -r

.I command

] [

.B -w

.I command

]

.I file

.SH DESCRIPTION

.I Pipefile

uses

.IR bind (2)

to attach a pair of pipes to

.IR file ,

using them to

interpose filter

.I commands

between the true file and the simulated file that subsequently

appears in the name space.

Option

.B -r

interposes a filter that will affect the data delivered to programs that read from

.IR file ;

.B -w

interposes a filter that will affect the data written by programs to

.IR file .

At least one

.I command

must be specified;

.I pipefile

will insert a

.IR cat (1)

process in the other direction.

.PP

After

.I pipefile

has been run, the filters are established for programs that subsequently

open the

.IR file ;

programs already using the

.I file

are unaffected.

.PP

.I Pipefile

opens the

.I file

twice, once for each direction.  If the

.I file

is a single-use device, such as

.BR /dev/mouse ,

use the

.B -d

flag to specify that the file is to be opened once, in

.B ORDWR

mode.

.SH EXAMPLES

Simulate an old terminal:

.EX

.IP

% pipefile -w 'tr a-z A-Z' /dev/cons

% rc -i </dev/cons >/dev/cons >[2=1]

% echo hello

HELLO

%

.EE

.PP

Really simulate an old terminal:

.EX

.IP

% pipefile -r 'tr A-Z a-z' -w 'tr a-z A-Z' /dev/cons

% rc -i </dev/cons >/dev/cons >[2=1]

% DATE

THU OCT 12 10:13:45 EDT 2000

%

.EE

.SH SOURCE

.B /sys/src/cmd/pipefile.c

.SH SEE ALSO

.IR mouse (8)

.SH BUGS

The I/O model of

.I pipefile

is peculiar; it doesn't work well on plain files.

It is really intended for use with continuous devices such as

.I /dev/cons

and

.IR /dev/mouse .

.I Pipefile

should be rewritten to be a user-level file system.

.PP

If the program using the file managed by

.I pipefile

exits, the filter will see EOF and exit, and the file will be unusable

until the name space is repaired.