Check the last comment in this case:
best-effort Commit the configuration changes via best-effort operation
comment Assign a comment to this commit
confirmed Rollback this commit unless there is a confirming commit
force Override the memory checks
label Assign a label to this commit
replace Replace the contents of running configuration
save-running Save running configuration to a file
show-error Displays commit failures immediately
<cr> Commit the configuration changes via pseudo-atomic operation
RP/0/RP0:IOS_XR9#copy running-config ?
WORD Copy to file
config: Copy to config: file system
disk0: Copy to disk0: file system
disk1: Copy to disk1: file system
ftp: Copy to ftp: file system
harddisk: Copy to harddisk: file system
http: Copy to http: file system
https: Copy to https: file system
rootfs: Copy to rootfs: file system
tftp: Copy to tftp: file system
IOS-XR is not the same as XE in many ways, one of them is how saving/storing config files work. XR-based platforms have a two-stage configuration scheme where:
1. Configuration is entered in a memory buffer first.
2. Configuration must then be applied by using commit command.
Running-config/startup-config does not technically exist, instead SysDB (EDM, and other processes that exist in LC/RSP) is the process in charge of configuration management.
If you want to wipe out all configurations from the XR device, you can enter into global configuration mode and execute the commit replace command.
Let know any questions.