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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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readcd dev=device [options]

Read or write compact discs. The device is usually specified as dev=scsibus/target/lun or dev=target/lun if the device is on the default SCSI bus). The default SCSI bus is bus 0, the target is the ID number, and the lun is the logical unit number.



Do a C2 error scan. If any C2 errors are found, specifying the speed= option to reduce the speed may help.


Read all data and the table of contents, and put the table-of-contents data into a file with the same filename as specified with f= but with a .toc extension.

-d, debug=num

Increment the debugging level by 1 with -d or set the level to num. Specifying -dd is the equivalent of debug=2.


Set the SCSI target.


Specify the file from which input should be read, or to which output should be written. If the filename is given as -, use standard input or standard output respectively.


Print the speed factor for the meshpoints= option, based on the current medium's single speed. Works only if readcd can determine the current medium type.


Read the full table of contents from the current CD and display it in hexadecimal.

kd=num, kdebug=num

Modify the kernel debugging level while SCSI commands are running, to do kernel debugging.


Print the read speed at num locations, and produce a list of values suitable for plotting. The output is written to standard output.


Ignore read errors, doing no error correction. Switches the drive into a mode to ignore the errors; if readcd completes, it switches the drive back to the previous mode.


Do not abort if an uncorrectable error is found in the data stream.


Do not truncate the output file on open.


Measure SCSI command overhead. The measurement is done by running several commands 1000 times and printing the total time used for each.


Set the retry count to num. The default is 128.

-s, -silent

Do not print a status report for SCSI command failures.


Scan all SCSI devices on all SCSI buses, print the results, and exit. Useful for finding the SCSI addresses of devices.


Specify the range of sectors to read.


Set the reading and writing speed, as an integer value. Useful only for MMC-compliant drives. Defaults to maximum speed.


Set the default SCSI command timeout to num seconds. Defaults to 40 seconds.


Set the maximum transfer size for a single SCSI command to num. Defaults to 256 KB.

-v, -verbose

Increment the general verbosity level by 1. Useful for displaying progress.

-V, -Verbose

Increment the verbosity level for SCSI command transport by 1. Useful for debugging. Specifying -VV adds data-buffer content to the output.


Print version information and exit.


Switch to write mode. The default is to read from the device.

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