In addition to the NX-OS CLI, Cisco Nexus 3000 Series devices support access to the Bourne-Again SHell (Bash). Bash interprets commands that you enter or commands that are read from a shell script. Using Bash enables access to the underlying Linux system on the device and to manage the system.

In Cisco NX-OS, Bash is accessible from user accounts that are associated with the Cisco NX-OS dev-ops role or the Cisco NX-OS network-admin role.

The following example shows the authority of the dev-ops role and the network-admin role:

switch# show role name dev-ops

Role: dev-ops
  Description: Predefined system role for devops access. This role
  cannot be modified.
  Vlan policy: permit (default)
  Interface policy: permit (default)
  Vrf policy: permit (default)
  -------------------------------------------------------------------
  Rule    Perm    Type        Scope               Entity
  -------------------------------------------------------------------
  4       permit  command                         conf t ; username *
  3       permit  command                         bcm module *
  2       permit  command                         run bash *
  1       permit  command                         python *

switch# show role name network-admin

Role: network-admin
  Description: Predefined network admin role has access to all commands
  on the switch
  -------------------------------------------------------------------
  Rule    Perm    Type        Scope               Entity
  -------------------------------------------------------------------
  1       permit  read-write
switch#

Bash is enabled by running the feature bash-shell command.

The run bash command loads Bash and begins at the home directory for the user.

The following examples show how to enable the Bash shell feature and how to run Bash.

switch# configure terminal
switch(config)# feature bash-shell

switch# run bash
Linux# whoami
admin
Linux# pwd
/bootflash/home/admin
Linux#

Note	You can also execute Bash commands with the run bash <command> command. The following is an example of the run bash <command> command. run bash whoami

The privileges of an admin user can escalate their privileges for root access. Root access is required to pass configuration commands to the NX-OS VSH.

The following are guidelines for escalating privileges:

• admin privilege user (network-admin / vdc-admin) is equivalent of Linux root privilege user in NX-OS

• Only an authenticated admin user can escalate privileges to root, and password is not required for an authenticated admin privilege user

• Bash must be enabled before escalating privileges.

• SSH to the switch using root username through a non-management interface will default to Linux Bash shell-type access for the root user. Type vsh to return to NX-OS shell access.

The following example shows how to escalate privileges to root and how to verify the escalation:

switch# run bash
Linux# sudo su root

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

Password:

Linux# whoami
root
Linux# exit
exit

This section contains examples of Bash commands and output.