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ab - Apache HTTP server benchmarking tool
ab [ -A auth-username:password ] [ -c concurrency ] [ -C cookie_name=value
] [ -d ] [ -e csv-file ] [ -g gnuplot-file ] [ -h ] [ -H
custom-header ] [ -i ] [ -k ] [ -n requests ] [ -p POST-file ] [ -P
proxy-auth-username:password ] [ -q ] [ -s ] [ -S ] [ -t timelimit ] [
-T content-type ] [ -v verbosity] [ -V ] [ -w ] [ -x <table>-attributes
] [ -X proxy[:port] ] [ -y <tr>-attributes ] [ -z <td>-attributes ]
ab is a tool for benchmarking your Apache Hypertext Transfer Protocol
(HTTP) server. It is designed to give you an impression of how your
current Apache installation performs. This especially shows you how
many requests per second your Apache installation is capable of serving.
Supply BASIC Authentication credentials to the server. The username
and password are separated by a single : and sent on the
wire base64 encoded. The string is sent regardless of whether
the server needs it (i.e., has sent an 401 authentication
- -c concurrency
Number of multiple requests to perform at a time. Default is one
request at a time.
- -C cookie-name=value
Add a Cookie: line to the request. The argument is typically in
the form of a name=value pair. This field is repeatable.
- Do not display the “percentage served within XX [ms] table".
- -e csv-file
Write a Comma separated value (CSV) file which contains for each
percentage (from 1% to 100%) the time (in milliseconds) it took
to serve that percentage of the requests. This is usually more
useful than the ‘gnuplot’ file; as the results are already
- -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 Excel. The
labels are on the first line of the file.
- Display usage information.
- -H custom-header
Append extra headers to the request. The argument is typically
in the form of a valid header line, containing a colon-separated
field-value pair (i.e., “Accept-Encoding: zip/zop;8bit").
- Do HEAD requests instead of GET.
- Enable the HTTP KeepAlive feature, i.e., perform multiple
requests within one HTTP session. Default is no KeepAlive.
- -n requests
Number of requests to perform for the benchmarking session. The
default is to just perform a single request which usually leads
to non-representative benchmarking results.
- -p POST-file
File containing data to POST.
- -P proxy-auth-username:password
Supply BASIC Authentication credentials to a proxy en-route. The
username and password are separated by a single : and sent on
the wire base64 encoded. The string is sent regardless of
whether the proxy needs it (i.e., has sent an 407 proxy authentication
- When processing more than 150 requests, ab outputs a progress
count on stderr every 10% or 100 requests or so. The -q flag
will suppress these messages.
- When compiled in (ab -h will show you) use the SSL protected
https rather than the http protocol. This feature is experimental
and very rudimentary. You probably do not want to use it.
- 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 deviation apart. And
default to the min/avg/max values. (legacy support).
- -t timelimit
Maximum number of seconds to spend for benchmarking. This
implies a -n 50000 internally. Use this to benchmark the server
within a fixed total amount of time. Per default there is no
- -T content-type
Content-type header to use for POST data.
- -v verbosity
Set verbosity level - 4 and above prints information on headers,
3 and above prints response codes (404, 200, etc.), 2 and above
prints warnings and info.
- Display version number and exit.
- Print out results in HTML tables. Default table is two columns
wide, with a white background.
- -x <table>-attributes
String to use as attributes for <table>. Attributes are inserted
<table here >.
- -X proxy[:port]
Use a proxy server for the requests.
- -y <tr>-attributes
String to use as attributes for <tr>.
- -z <td>-attributes
String to use as attributes for <td>.
There are various statically declared buffers of fixed length. Combined
with the lazy parsing of the command line arguments, the response headers
from the server and other external inputs, this might bite you.
It does not implement HTTP/1.x fully; only accepts some ‘expected’
forms of responses. The rather heavy use of strstr(3)
shows up top in
profile, which might indicate a performance problem; i.e., you would
measure the ab performance rather than the server’s.
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