parrot_run - run a program in the Parrot virtual file system


parrot_run [parrot_options] program [program_options]


parrot_run runs an application or a shell inside the Parrot virtual filesystem. Parrot redirects the application's system calls to remote storage systems. Parrot currently supports the following remote storage systems: HTTP, GROW, FTP, GridFTP, iRODS, HDFS, XRootd, Chirp. This list may vary depending on how Parrot was built. Run parrot -h to see exactly what support is available on your system.

Parrot works by trapping the application's system calls through the ptrace debugging interface. It does not require any special privileges to install or run, so it is useful to ordinary users that wish to access data across wide area networks. The ptrace debugging interface does have some cost, so applications may run slower, depending on how many I/O operations they perform.

For complete details with examples, see the Parrot User's Manual


  • --check-driver=<driver>
    Check for the presence of a given driver (e.g. http, ftp, etc) and return success if it is currently enabled.
  • -a,--chirp-auth=<unix|hostname|ticket|globus|kerberos>
    Use this Chirp authentication method. May be invoked multiple times to indicate a preferred list, in order.
  • -b,--block-size=<bytes>
    Set the I/O block size hint.
  • -c,--status-file=<file>
    Print exit status information to file.
  • -C,--channel-auth
    Enable data channel authentication in GridFTP.
  • -d,--debug=<flag>
    Enable debugging for this sub-system.
  • -D,--no-optimize
    Disable small file optimizations.
  • --dynamic-mounts
    Enable the use of parot_mount in this session.
  • -F,--with-snapshots
    Enable file snapshot caching for all protocols.
  • -f,--no-follow-symlinks
    Disable following symlinks.
  • -G,--gid=<num>
    Fake this gid; Real gid stays the same.
  • -h,--help
    Show this screen.
  • ----helper
    Enable use of helper library.
  • -i,--tickets=<files>
    Comma-delimited list of tickets to use for authentication.
  • -I,--debug-level-irods=<num>
    Set the iRODS driver internal debug level.
  • -K,--with-checksums
    Checksum files where available.
  • -k,--no-checksums
    Do not checksum files.
  • -l,--ld-path=<path>
    Path to to use.
  • -m,--ftab-file=<file>
    Use this file as a mountlist.
  • -M,--mount=</foo=/bar>
    Mount (redirect) /foo to /bar.
  • -e,--env-list=<path>
    Record the environment variables.
  • -n,--name-list=<path>
    Record all the file names.
  • --no-set-foreground
    Disable changing the foreground process group of the session.
  • -N,--hostname=<name>
    Pretend that this is my hostname.
  • -o,--debug-file=<file>
    Write debugging output to this file. By default, debugging is sent to stderr (":stderr"). You may specify logs to be sent to stdout (":stdout") instead.
  • -O,--debug-rotate-max=<bytes>
    Rotate debug files of this size.
  • -p,--proxy=<host:port>
    Use this proxy server for HTTP requests.
  • -Q,--no-chirp-catalog
    Inhibit catalog queries to list /chirp.
  • -r,--cvmfs-repos=<repos>
    CVMFS repositories to enable (PARROT_CVMFS_REPO).
  • --cvmfs-repo-switching
    Allow repository switching with CVMFS.
  • -R,--root-checksum=<cksum>
    Enforce this root filesystem checksum, where available.
  • -s,--stream-no-cache
    Use streaming protocols without caching.
  • -S,--session-caching
    Enable whole session caching for all protocols.
  • --syscall-disable-debug
    Disable tracee access to the Parrot debug syscall.
  • -t,--tempdir=<dir>
    Where to store temporary files.
  • -T,--timeout=<time>
    Maximum amount of time to retry failures. time)Maximum amount of time to retry failures.
  • --time-stop
    Stop virtual time at midnight, Jan 1st, 2001 UTC.
  • --time-warp
    Warp virtual time starting from midnight, Jan 1st, 2001 UTC.
  • -U,--uid=<num>
    Fake this unix uid; Real uid stays the same.
  • -u,--username=<name>
    Use this extended username.
  • --fake-setuid
    Track changes from setuid and setgid.
  • --valgrind
    Enable valgrind support for Parrot.
  • -v,--version
    Display version number.
  • --is-running
    Test is Parrot is already running.
  • -w,--work-dir=<dir>
    Initial working directory.
  • -W,--syscall-table
    Display table of system calls trapped.
  • -Y,--sync-write
    Force synchronous disk writes.
  • -Z,--auto-decompress
    Enable automatic decompression on .gz files.
  • --disable-service=<service>
    Disable a compiled-in service (e.g. http, cvmfs, etc.)


parrot_run sets the environment variable PARROT_ENABLED to the value 1 for its child processes. This makes it possible to set a visible flag in your shell prompt when parrot_run is enabled.


parrot_run returns the exit status of the process that it runs. If parrot_run is unable to start the process, it will return non-zero.


To access a single remote file using vi:

% parrot_run vi /anonftp/

You can also run an entire shell inside of Parrot, like this:

% parrot_run bash
% cd /anonftp/
% ls -la
% cat README
% exit

To see the list of available Chirp servers around the world:

% parrot_run ls -la /chirp

Parrot can record the names of all the accessed files and the environment variables during the execution process of one program, like this:

% parrot_run --name-list list.txt --env-list envlist ls ~
The environment variables at the starting moment of your program will be recorded into envlist. The absolute paths of all the accessed files, together with the system call types, will be recorded into list.txt. For example, the file /usr/bin/ls is accessed using the stat system call, like this:
% /usr/bin/ls|stat


Docker by default blocks ptrace, the system call on which parrot relies. To run parrot inside docker, the container needs to be started using the --security-opt seccomp=unconfined command line argument. For example:

    docker run --security-opt seccomp=unconfined MY-DOCKER-IMAGE

The Cooperative Computing Tools are Copyright (C) 2022 The University of Notre Dame. This software is distributed under the GNU General Public License. See the file COPYING for details.