ODO(1)ODO(1)NAMEodo - an atomic odometer for the command line
SYNOPSISodo [-c | -i | -r | -s COUNT] [-p] file
DESCRIPTIONodo atomically updates a count in a file, which will be created if not
present. The count is text-formatted (e.g. "00012345\n"), and will be
accurately incremented or reset even when multiple processes attempt to
change the counter at the same time. (It uses memory mapping and atomic
compare-and-swap operations to eliminate race conditions.)
This could be used to track some intermittent event, like services
being restarted. Since the counter is just a number in a text file,
it´s easy ls to compose odo with other tools.
OPTIONS
These options impact how the counter is updated:
-c Print the current counter value without updating.
-i Increment the counter. (This is the default.)
-r Reset the counter to 0.
-s COUNT
Update the counter to a specific value.
-p Print the new value of the counter after updating.
EXIT STATUS
Returns 0 if the counter has been successfully updated. Returns 1 if
the file could not be read, created, or written, or if its current con‐
tents do not match the expected format of a counter file.
EXAMPLES
This atomically increments a counter in /log/restarts. If the counter
file does not exist, it is created as 0 and incremented to 1.
$ odo /log/restarts
Same, but print the updated count:
$ odo-p /log/restarts
Reset the count to 0:
$ ./odo -r /log/restarts
Set the count to a number (for testing notifications, perhaps):
$ ./odo -s 12345 /log/restarts
Print the current counter value without incrementing:
$ ./odo -c /log/restarts
Print usage / help:
$ ./odo -h
BUGS
odo´s atomicity is only as reliable as the underlying filesystem´s.
Inconsistencies may still occur if used on a non-local filesystems such
as nfs.
COPYRIGHTodo is Copyright (C) 2014 Scott Vokes scott.vokes@atomicobject.com.
SEE ALSOrunit(8), sqlite3(1), nfsd(8)
November 2014 ODO(1)
