pcsc-spy - Man Page

A PC/SC spy command


pcsc-spy [-n|--nocolor] [-d|--diffable] [-h|--help] [-v|--version] [-t|--thread] [fifo_filename]


pcsc-spy displays PC/SC calls of an application. It must be used with the libpcscspy.so library.

To be able to spy the PC/SC layer, the application flow must be modified so that all PC/SC calls are redirected. Two options are available:

- the application is linked with libpcsclite.so.1

- the application loads the libpcsclite.so.1 library using dlopen(3)


-d,  --diffable

Remove the variable parts (like handler values) from the output so that two execution can be more easily compared.

-h,  --help

Display a short help text.

-n,  --nocolor

Disable the output colorization (if you want redirect the output in a file for example).

-v,  --version

Print the version of the pcsc-spy program plus a copyright, a list of authors.

-t,  --thread

Add a thread number before each line of log to identify the calls from the same threads.


Applications linked with libpcsclite.so.1

We will use the standard LD_PRELOAD loader option to load our spying library.


 LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libpcscspy.so pcsc_scan

Application loading libpcsclite.so.1

This is the case for the PC/SC wrappers like pyscard (for Python) and pcsc-perl (for Perl). The LD_PRELOAD mechanism can't be used. Instead we replace the libpcsclite.so.1 library by the spying one.

You may use install_spy.sh and uninstall_spy.sh to install and uninstall the spying library.

Using the spying library without pcsc-spy is not a problem but has side effects:

- a line "libpcsclite_nospy.so.1: cannot open shared object file: No such file or directory" will be displayed

- some CPU time will be lost because of the PC/SC calls redirection

Starting the spy tool


If a command argument is passed we use it instead of the default ~/pcsc-spy FIFO file. It is then possible to record an execution log and use pcsc-spy multiple times on the same log.

To create the log file just do:

 mkfifo ~/pcsc-spy
 cat ~/pcsc-spy > logfile

and run your PC/SC application.


~/pcsc-spy FIFO file is used by libpcsclite.so.1 to send the raw log lines

See Also



This manual page was written by Ludovic Rousseau <rousseau@free.fr>


2024-01-25 pcsc-lite 2.0.1 PC/SC lite