nsswitch.conf
A description of the Name Service Switch (NSS) file (/etc/nsswitch.conf). For more details, see nsswitch.conf(5).
Example
passwd: compat group: compat shadow: compat hosts: dns [!UNAVAIL=return] files networks: nis [NOTFOUND=return] files ethers: nis [NOTFOUND=return] files protocols: nis [NOTFOUND=return] files rpc: nis [NOTFOUND=return] files services: nis [NOTFOUND=return] files
Syntax
Databases
The first column (delimited by spaces or tab characters) indicates a database, while every subsequent column is a service specification or optional action.
Service Specifications
Common service specifications are:
files (i.e. /etc/hosts)
dns (i.e. runtime lookups based on /etc/resolv.conf)
myhostname (see nss-myhostname(8))
mymachine which connects to systemd-machined (see nss-mymachines(8))
resolve which connects to systemd-resolved (see nss-resolve(8))
Optional Actions
Option actions follow the pattern of [STATUS=ACTION] and [!STATUS=ACTION].
A status can be any of:
success meaning 'no error'.
notfound meaning 'error in lookup'.
unavail indicates a connection couldn't be made.
tryagain indicates 'temporarily unavailability', as with locked connections.
An action can be any of:
return meaning 'return the result'
continue meaning 'try the next item'
merge causes the system to try both the preceding and the following items
By default, only a success status results in a return action. Anything else will result in a continue. The exception the group database, where a notfound status will lead to a continue action regardless of any action specified.