The user is greeted with the Linux shell when accessing the SONiC NOS. The list of Linux shell commands available is invoked by typing help.

admin@Leaf1:~$ help
GNU bash, version 4.4.12(1)-release (x86_64-pc-linux-gnu)
These shell commands are defined internally.  Type `help' to see this list.
Type `help name' to find out more about the function `name'.
Use `info bash' to find out more about the shell in general.
Use `man -k' or `info' to find out more about commands not in this list.
A star (*) next to a name means that the command is disabled.
job_spec [&]                            history [-c] [-d offset] [n] or hist>
 (( expression ))                        if COMMANDS; then COMMANDS; [ elif C>
 . filename [arguments]                  jobs [-lnprs] [jobspec ...] or jobs >
 :                                       kill [-s sigspec | -n signum | -sigs>
 [ arg... ]                              let arg [arg ...]
 [[ expression ]]                        local [option] name[=value] ...
 alias [-p] [name[=value] ... ]          logout [n]
 bg [job_spec ...]                       mapfile [-d delim] [-n count] [-O or>
 bind [-lpsvPSVX] [-m keymap] [-f file>  popd [-n] [+N | -N]
 break [n]                               printf [-v var] format [arguments]
 builtin [shell-builtin [arg ...]]       pushd [-n] [+N | -N | dir]
 caller [expr]                           pwd [-LP]
***** OUTPUT TRUNCATED *****

Note: The preceding code is from the Device information section of https://github.com/Azure/SONiC/wiki/Configuration-with-Minigraph-(~Sep-2017).

For example, the command to list the contents of the folder sonic is listed below:

admin@Leaf1:~$ ls /etc/sonic/
agent_config.cfg      frr                      snmp.yml
asic_config_checksum  generated_services.conf  sonic_branding.yml
config_db.json        hamd                     sonic_version.yml
constants.yml         init_cfg.json            updategraph.conf

Another example to view the contents of the config_db.json file is shown below:

admin@Leaf1:~$ cat /etc/sonic/config_db.json
{
    "DEVICE_METADATA": {
        "localhost": {
            "docker_routing_config_mode": "split",
            "hostname": "Leaf1",
            "hwsku": "DellEMC-S5248f-P-25G",
            "mac": "8c:04:ba:a7:ee:c0",
            "platform": "x86_64-dellemc_s5248f_c3538-r0",
            "type": "LeafRouter"
        }
    },
    "FLEX_COUNTER_TABLE": {
        "PFCWD": {
            "FLEX_COUNTER_STATUS": "enable"
        },
        "PORT": {
            "FLEX_COUNTER_STATUS": "enable"
        },
        "QUEUE": {
            "FLEX_COUNTER_STATUS": "enable"
        }
    },
    "HARDWARE": {
        "ACCESS_LIST": {
            "COUNTER_MODE": "per-rule",
            "LOOKUP_MODE": "optimized"
        }
    },
    "INTERFACE": {
        "Ethernet52": {
            "ipv6_use_link_local_only": "enable"
        }
    },
    "LOOPBACK_INTERFACE": {
        "Loopback0": {},
        "Loopback0|10.0.1.1/32": {}
    },
    "MGMT_INTERFACE": {
        "eth0": {},
        "eth0|100.67.204.35/24": {}
    },
    "MGMT_PORT": {
        "eth0": {
            "admin_status": "up",
            "autoneg": "true",
            "description": "Management0",
            "mtu": "1500",
            "speed": "1000"
        }
    }
***** OUTPUT TRUNCATED *****