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entwatch.1
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.\" Process this file with
.\" groff -man -Tascii entwatch.1
.\"
.TH ENTWATCH 1 "April 2012" Linux "User Manuals"
.SH NAME
entwatch \- monitor the kernel entropy level from the console.
.SH SYNOPSIS
.B entwatch [-wh] [-r
.I rand-path
.B ]
.SH DESCRIPTION
.B entwatch
polls the kernel entropy pool, and emits each reading to standard output.
By default, it accesses the kernel via the file found at
.IR /dev/random ,
and waits one second between reports.
While the user may query the entropy pool by reading the file
.I /proc/sys/kernel/random/entropy_avail
with a command like
.BR cat (1),
doing so consumes kernel entropy as a result of Address Space Layout
Randomization (ASLR). Using
.BR entwatch (1)
to perform successive reads ensures that the user only spend entropy on
ASLR once for the purpose.
.SH OPTIONS
.IP "-w, --wait=SECONDS"
Wait
.I SECONDS
seconds between reports.
.IP "-r, --rand-path=PATH"
Use the file specified by
.I PATH
instead of the default file
.IR /dev/random .
.IP "-h, --help"
Print options and usage information.
.SH FILES
.I /dev/random
.RS
The file
.BR entwatch (1)
will perform ioctls on, by default.
.SH ENVIRONMENT
No environment variables are paid particular attention by
.BR entwatch (1) .
.SH DIAGNOSTICS
The following diagnostics may be issued on standard error:
Error wait time must be greater than 0.
.RS
The wait time passed on the command line was not an integer greater than 0.
.RE
Error opening
.IR file :
.I reason
.RS
.BR entwatch
was unable to open the random device file
.IR file .
The system libc's error is given for further diagnostics.
.RE
Error with ioctl call on
.IR file :
.I reason
.RS
.BR entwatch
failed to issue its querying ioctl on the random device file
.IR file .
The system libc's error is given for further diagnostics.
.SH BUGS
Since
.BR entwatch (1)
was first written,
.BR entbuff (8)
evolved significantly more functionality and configurability, including an improved code style and differing command-line units for similar parameters.
.BR entwatch (1)
should be brought up to snuff.
.SH AUTHOR
Michael Mol <mikemol at gmail dot com>
(And more; see AUTHORS file)
.SH "SEE ALSO"
.BR entbuff (8),
.BR /usr/src/linux/drivers/char/random.c