Add detach in scope cli

[michalbiesek]

Ref #1107

- [ ] Handle the scenario when we attach to an already scoped process should we overwrite the scope configuration always?
We overwrite the configuration during reattach

[michalbiesek]

The logic is ready to review. I am not sure which docs section should be updated/extended regarding the detach, e.g.:

appscope/website/src/pages/docs/overview.md

Lines 21 to 23 in 6a9106e

	- Instrument both static and dynamic executables.
	- Attach to processes *while they are running* or start when the process does.
	- Run on Alpine Linux, another Linux distribution based on musl libc, or on a glibc-based distro.

"Attach to processes while they are running or start when the process does."
cc @abetones

[seanvaleo]

I get this message when re-attaching multiple times quickly ; or detaching multiple times quickly:
open() of dynamic config file: Permission denied
I understand why, and that it's a library error not a cli error, but maybe we just handle it with a cleaner message in this case?

[seanvaleo]

If i run top in two terminals then:
scope attach top to bring up the selection menu.
Whatever I choose, I get:
PID does not exist

[michalbiesek]

If i run top in two terminals then:
scope attach top to bring up the selection menu.
Whatever I choose, I get:
PID does not exist

Good catch - done in 853fa85

[michalbiesek]

I get this message when re-attaching multiple times quickly ; or detaching multiple times quickly: open() of dynamic config file: Permission denied I understand why, and that it's a library error not a cli error, but maybe we just handle it with a cleaner message in this case?

I have created an issue for this: #1123 . I think this can be somehow handled by modifying creation of our file because I believe the issue is related to file sealing. I did not observe a similar problem if I change the location

appscope/src/scopetypes.h

Line 259 in 6a9106e

#define DYN_CONFIG_CLI_DIR "/dev/shm"

to /tmp