ab(1)ab(1)NAMEab - Apache HTTP server benchmarking tool
SYNOPSISab [ -k ] [ -e ] [ -q ] [ -S ] [ -i ] [ -s ] [ -n requests ] [ -t time‐
limit ] [ -c concurrency ] [ -p POST file ] [ -A Authenticate user‐
name:password ] [ -X proxy [ :port ] ] [ -P Proxy Authenticate user‐
name:password ] [ -H Custom header ] [ -C Cookie name=value ] [ -T con‐
tent-type ] [ -v verbosity ] ] [ -w output HTML ] ] [ -g output GNUPLOT
] ] [ -e output CSV ] ] [ -x <table> attributes ] ] [ -y <tr>
attributes ] ] [ -z <td> attributes ] [http[s]://]hostname[:port]/path
ab [ -V ] [ -h ]
DESCRIPTIONab is a tool for benchmarking the performance of your Apache HyperText
Transfer Protocol (HTTP) server. It does this by giving you an indica‐
tion of how many requests per second your Apache installation can
OPTIONS-k Enable the HTTP KeepAlive feature; that is, perform multi‐
ple requests within one HTTP session. Default is no
-d Do not display the "percentage served within XX [ms] ta‐
ble". (legacy support).
-S Do not display the median and standard deviation values,
nor display the warning/error messages when the average and
median are more than one or two times the standard devia‐
tion apart. And default to the min/avg/max values. (legacy
-s When compiled in (bb -h will show you) use the SSL pro‐
tected https rather than the http protocol. This feature is
experimental and very rudimentary. You propably do not want
to use it.
-k Enable the HTTP KeepAlive feature; that is, perform multi‐
ple requests within one HTTP session. Default is no
KeepAlive. -i Use an HTTP 'HEAD' instead of the GET
method. Cannot be mixed with POST.
-n requests The number of requests to perform for the benchmarking ses‐
sion. The default is to perform just one single request,
which will not give representative benchmarking results.
The number of seconds to spend benchmarking. Using this
option automatically set the number of requests for the
benchmarking session to 50000. Use this to benchmark the
server for a fixed period of time. By default, there is no
The number of simultaneous requests to perform. The default
is to perform one HTTP request at at time, that is, no con‐
-p POST file
A file containing data that the program will send to the
Apache server in any HTTP POST requests.
-A Authorization username:password
Supply Basic Authentication credentials to the server. The
username and password are separated by a single ':', and
sent as uuencoded data. The string is sent regardless of
whether the server needs it; that is, has sent a 401
Route all requests through the proxy (at optional port).
-P Proxy-Authorization username:password
Supply Basic Authentication credentials to a proxy en-
route. The username and password are separated by a single
':', and sent as uuencoded data. The string is sent
regardless of whether the proxy needs it; that is, has sent
a 407 Proxy authentication needed.
-C Cookie name=value
Add a 'Cookie:' line to the request. The argument is typi‐
cally a 'name=value' pair. This option may be repeated.
-p Header string
Append extra headers to the request. The argument is typi‐
cally in the form of a valid header line, usually a colon
separated field value pair, for example, 'Accept-Encoding:
The content-type header to use for POST data.
-g gnuplot file
Write all measured values out as a 'gnuplot' or TSV (Tab
separate values) file. This file can easily be imported
into packages like Gnuplot, IDL, Mathematica, Igor or even
Excell. The labels are on the first line of the file.
-q When processing more than 150 requsts; ab outputs a
progress count on stderr every 10% or 100 requests or so.
The -q flag qill suppress these messages.
-e CSV file Write a Comma separated value (CSV) file which contains for
each percentage (from 1% to 100%) the time (in milli sec‐
onds) it took to serve that percentage of the requests.
This is usually more usefull than the 'gnuplot' file; as
the results are already
-v Sets the verbosity level. Level 4 and above prints infor‐
mation on headers, level 3 and above prints response codes
(for example, 404, 200), and level 2 and above prints warn‐
ings and informational messages.
-w Print out results in HTML tables. The default table is two
columns wide, with a white background.
The string to use as attributes for <table>. Attributes
are inserted <table here >
The string to use as attributes for <tr>.
The string to use as attributes for <td>.
-V Display the version number and exit.
-h Display usage information.
There are various statically declared buffers of fixed length. Combined
with inefficient parsing of the command line arguments, the response
headers from the server, and other external inputs, these buffers might
Ab does not implement HTTP/1.x fully; instead, it only accepts some
'expected' forms of responses.
The rather heavy use of strstr(3) by the program may skew performance
results, since it uses significant CPU resources. Make sure that per‐
formance limits are not hit by ab before your server's limit is
The HTML output is not as complete as the text output.
Up to version 1.3d ab has propably reported values way to low for most
measurements; as a single timeout (which is usually in the order of
seconds) will shift several thousands of milli-second responses by a
considerable factor. This was further componded by a serious interger
overrun which would for realistic run's (i.e. those longer than a few
minutes) produce believable but totally bogus results. Thanks to Sander
Temme for solving this riddle.
October 1999 ab(1)