<s>
agrep	B-Device
(	O
approximate	B-Device
grep	I-Device
)	O
is	O
an	O
open-source	B-Application
approximate	B-Algorithm
string	I-Algorithm
matching	I-Algorithm
program	O
,	O
developed	O
by	O
Udi	O
Manber	O
and	O
Sun	O
Wu	O
between	O
1988	O
and	O
1991	O
,	O
for	O
use	O
with	O
the	O
Unix	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
It	O
was	O
later	O
ported	O
to	O
OS/2	B-Application
,	O
DOS	B-Device
,	O
and	O
Windows	B-Application
.	O
</s>
<s>
It	O
selects	O
the	O
best-suited	O
algorithm	O
for	O
the	O
current	O
query	O
from	O
a	O
variety	O
of	O
the	O
known	O
fastest	O
(	O
built-in	O
)	O
string	B-Algorithm
searching	I-Algorithm
algorithms	I-Algorithm
,	O
including	O
Manber	O
and	O
Wu	O
's	O
bitap	B-Algorithm
algorithm	I-Algorithm
based	O
on	O
Levenshtein	O
distances	O
.	O
</s>
<s>
agrep	B-Device
is	O
also	O
the	O
search	O
engine	O
in	O
the	O
indexer	O
program	O
GLIMPSE	O
.	O
</s>
<s>
agrep	B-Device
is	O
under	O
a	O
free	O
ISC	B-License
License	I-License
.	O
</s>
<s>
A	O
more	O
recent	O
agrep	B-Device
is	O
the	O
command-line	O
tool	O
provided	O
with	O
the	O
TRE	B-Algorithm
regular	B-Language
expression	I-Language
library	O
.	O
</s>
<s>
TRE	B-Algorithm
agrep	B-Device
is	O
more	O
powerful	O
than	O
Wu-Manber	B-Algorithm
agrep	B-Device
since	O
it	O
allows	O
weights	O
and	O
total	O
costs	O
to	O
be	O
assigned	O
separately	O
to	O
individual	O
groups	O
in	O
the	O
pattern	O
.	O
</s>
<s>
Unlike	O
Wu-Manber	B-Algorithm
agrep	B-Device
,	O
TRE	B-Algorithm
agrep	B-Device
is	O
licensed	O
under	O
a	O
2-clause	O
BSD-like	O
license	O
.	O
</s>
<s>
FREJ	O
(	O
Fuzzy	O
Regular	B-Language
Expressions	I-Language
for	O
Java	O
)	O
open-source	B-Application
library	O
provides	O
command-line	O
interface	O
which	O
could	O
be	O
used	O
in	O
the	O
way	O
similar	O
to	O
agrep	B-Device
.	O
</s>
<s>
Unlike	O
agrep	B-Device
or	O
TRE	B-Algorithm
it	O
could	O
be	O
used	O
for	O
constructing	O
complex	O
substitutions	O
for	O
matched	O
text	O
.	O
</s>
<s>
However	O
its	O
syntax	O
and	O
matching	O
abilities	O
differs	O
significantly	O
from	O
ones	O
of	O
ordinary	O
regular	B-Language
expressions	I-Language
.	O
</s>
