oreilly.comSafari Books Online.Conferences.


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.

Buy it now, or read it online on Safari Bookshelf.


ssh-keygen [options]

Generate, manage, and convert authentication keys for ssh. When using ssh-keygen to create a key, the -t option must be specified to identify the type of key to create.


-b bits

Specify the number of bits in the key. The minimum is 512, and the default is 1024.


Show the bubblebabble digest (a digest represented as a string that looks like real words) for the private or public keyfile specified with -f.


Change the comment in the private and public keyfiles (for RSA1 keys only).

-C comment

Specify the new comment.

-D reader

Download the RSA public key from the smartcard in reader.


Read an OpenSSH private or public keyfile and write it in SECSH Public Key File Format to standard output for exporting to a commercial SSH.

-f file

Specify the filename of the keyfile.


Read an SSH2-compatible unencrypted private or public keyfile and write an OpenSSH-compatible key to standard output. Used to import keys from a commercial SSH.


Show fingerprint of public or private RSA1 keyfile specified with -f.

-N passphrase

Specify the new passphrase.


Change the passphrase for a private keyfile. Prompt for the file, the old passphrase, and twice for the new passphrase.

-P passphrase

Specify the old passphrase.


Operate in quiet mode.

-t type

Specify the type of key to create. Possible values of type are rsa1 for SSH1, and rsa or dsa for SSH2.

-U reader

Upload an existing RSA private key to the smartcard in reader.


Read a private OpenSSH-format file and print a public key to standard output.

Linux Resources
  • Linux Online
  • The Linux FAQ
  • Linux Kernel Archives
  • Kernel Traffic

  • Sponsored by: