Chapter 11.  Accessing Client Resources from the ThinLinc session

Table of Contents

11.1. Accessing the Clients Local Drives
11.1.1. Introduction
11.1.2. Mounting and Unmounting Local Drives
11.1.3. Mounting Drives at Login
11.1.4. Limitations and additional information
11.2. Using Serial Port redirection
11.2.1. Introduction
11.2.2. Requirements
11.2.3. Enabling Serial Port Redirection
11.2.4. Accessing the redirected port from applications
11.2.5. Limitations and additional information
11.3. Using Sound Device Redirection
11.3.1. Introduction
11.3.2. Requirements
11.3.3. PulseAudio applications
11.3.4. OSS applications
11.3.5. ALSA applications
11.3.6. Choosing sound system
11.3.7. Limitations and additional information
11.4. Using Smart Card Redirection
11.4.1. Introduction
11.4.2. Requirements
11.4.3. Enabling Smart Card Redirection
11.4.4. Limitations and additional information

In this chapter we will describe how to access client resources, such as local drives and serial ports, from the ThinLinc session.

11.1.  Accessing the Clients Local Drives

11.1.1.  Introduction

Using ThinLinc, it is possible to access the clients' drives and filesystems from the ThinLinc session. With thin terminals, one might want to access a local CD-ROM drive. When running the client on a workstation, applications on the remote desktop server can access all filesystems mounted at the workstation, just like local applications can.

Note

Many Digital Cameras can be accessed as a USB storage device, and can be exported as a local drive.

11.1.2.  Mounting and Unmounting Local Drives

The exported local drives can be mounted with the command tl-mount-localdrives . The drives will be mounted below $TLSESSIONDATA/drives. A symbolic link called "thindrives" will be created in the user's home directory, pointing to this directory. The syntax for tl-mount-localdrives is:

tl-mount-localdrives [-h] [-v]

The -v option causes the tool to be executed in verbose mode, while -h shows the syntax.

The Hiveconf parameter /utils/tl-mount-localdrives/mount_args specifies the mount arguments. This Hiveconf parameter is normally found in /opt/thinlinc/etc/conf.d/tl-mount-localdrives.hconf. The options mountport, port, mountvers, nfsvers, nolock, and tcp will always be used.

Mounted local drives can be unmounted with the command tl-umount-localdrives .If some applications are using a mount at this time, they can continue to access the mount, even though the mount has been removed from the filesystem hierarchy (so called "lazy" umount). The syntax for tl-umount-localdrives is:

tl-umount-localdrives [-a] [-s] [-l]

If -a is specified, then all mounted local drives, for all users on this machine, will be unmounted. If -s is specified, then all mounted local drives, for all sessions belonging to the current user, will be unmounted. If -l is specified, the thindrives link will not be updated.

Note

When using multiple sessions per user, the thindrives link will point to the newest session that executed tl-mount-localdrives. tl-umount-localdrives will restore the link to the newest session which is not newer than the current session and which has mounted local drives.

11.1.3.  Mounting Drives at Login

Often, it's convenient to automatically mount all local drives for a user when the session starts. This is done by default via a symbolic link in /opt/thinlinc/etc/xstartup.d, pointing at /opt/thinlinc/bin/tl-mount-localdrives. This link is created for you during installation, as well as its counterpart in /opt/thinlinc/etc/xlogout.d which points to /opt/thinlinc/bin/tl-umount-localdrives.

11.1.4.  Limitations and additional information

  • Linux kernel 2.6.23 or later is required.

  • A mounted local drive, for example /var/opt/thinlinc/sessions/johndoe/47/drives/cdrom, is only usable during the lifetime of the ThinLinc session. If the user ends the session without unmounting and then starts a new session, the mount will not be usable even if the session number happens to be same. In this case, any attempts to access the mount will give the error message "Stale NFS file handle". To be able to use the local drive, the user needs to run tl-mount-localdrives .

  • The mounted local drive does not fully support POSIX semantics. The usual limitations of NFSv3 applies. Additionally, if the file is moved to another directory while a process has the file open, the process will get a "Stale NFS file handle" error on any subsequent file operation for that file.

  • Local files are uniquely identified by their inode number. Some file system implementations, such as the Linux kernel FAT implementation, do not provide persistant inode numbers. Inode numbers will change on each remount, which usually results in "Stale NFS file handle" errors.