I recognize that the first part of this question resembles others here, but those answers DO NOT appear to work! If you wish to combine this with Can I exit from a specific country or node?, fine.
I use "Onion Circuits" to observe the results of my work; and I log in as "admin", with persistence enabled [if relevant].
The torrc file at /etc/tor/torrc is "Read Only"; so editing it with "gedit" or "LibreOffice Writer" does not work.
I have used the following commands to append the code that they generate to the end of my torrc file [which does appear there].
echo ExcludeSingleHopRelays 1 | sudo tee -a /etc/tor/torrc
echo AllowSingleHopCircuits 0 | sudo tee -a /etc/tor/torrc
echo ExitNodes "{us}" | sudo tee -a /etc/tor/torrc
echo ExcludeExitNodes "{AA},{AB},{AC},{AD},{AE},{AF},{AG},{AH},{AI},{AJ},{AK},{AL},{AM},{AN},{AO},{AP},{AQ},{AR},{AS},{AT},{AU},{AV},{AW},{AX},{AY},{AZ},{BA},{BB},{BC},{BD},{BE},{BF},{BG},{BH},{BI},{BJ},{BK},{BL},{BM},{BN},{BO},{BP},{BQ},{BR},{BS},{BT},{BU},{BV},{BW},{BX},{BY},{BZ},{CA},{CB},{CC},{CD},{CE},{CF},{CG},{CH},{CI},{CJ},{CK},{CL},{CM},{CN},{CO},{CP},{CQ},{CR},{CS},{CT},{CU},{CV},{CW},{CX},{CY},{CZ},{DA},{DB},{DC},{DD},{DE},{DF},{DG},{DH},{DI},{DJ},{DK},{DL},{DM},{DN},{DO},{DP},{DQ},{DR},{DS},{DT},{DU},{DV},{DW},{DX},{DY},{DZ},{EA},{EB},{EC},{ED},{EE},{EF},{EG},{EH},{EI},{EJ},{EK},{EL},{EM},{EN},{EO},{EP},{EQ},{ER},{ES},{ET},{EU},{EV},{EW},{EX},{EY},{EZ},{FA},{FB},{FC},{FD},{FE},{FF},{FG},{FH},{FI},{FJ},{FK},{FL},{FM},{FN},{FO},{FP},{FQ},{FR},{FS},{FT},{FU},{FV},{FW},{FX},{FY},{FZ},{GA},{GB},{GC},{GD},{GE},{GF},{GG},{GH},{GI},{GJ},{GK},{GL},{GM},{GN},{GO},{GP},{GQ},{GR},{GS},{GT},{GU},{GV},{GW},{GX},{GY},{GZ},{HA},{HB},{HC},{HD},{HE},{HF},{HG},{HH},{HI},{HJ},{HK},{HL},{HM},{HN},{HO},{HP},{HQ},{HR},{HS},{HT},{HU},{HV},{HW},{HX},{HY},{HZ},{IA},{IB},{IC},{ID},{IE},{IF},{IG},{IH},{II},{IJ},{IK},{IL},{IM},{IN},{IO},{IP},{IQ},{IR},{IS},{IT},{IU},{IV},{IW},{IX},{IY},{IZ},{JA},{JB},{JC},{JD},{JE},{JF},{JG},{JH},{JI},{JJ},{JK},{JL},{JM},{JN},{JO},{JP},{JQ},{JR},{JS},{JT},{JU},{JV},{JW},{JX},{JY},{JZ},{KA},{KB},{KC},{KD},{KE},{KF},{KG},{KH},{KI},{KJ},{KK},{KL},{KM},{KN},{KO},{KP},{KQ},{KR},{KS},{KT},{KU},{KV},{KW},{KX},{KY},{KZ},{LA},{LB},{LC},{LD},{LE},{LF},{LG},{LH},{LI},{LJ},{LK},{LL},{LM},{LN},{LO},{LP},{LQ},{LR},{LS},{LT},{LU},{LV},{LW},{LX},{LY},{LZ},{MA},{MB},{MC},{MD},{ME},{MF},{MG},{MH},{MI},{MJ},{MK},{ML},{MM},{MN},{MO},{MP},{MQ},{MR},{MS},{MT},{MU},{MV},{MW},{MX},{MY},{MZ},{NA},{NB},{NC},{ND},{NE},{NF},{NG},{NH},{NI},{NJ},{NK},{NL},{NM},{NN},{NO},{NP},{NQ},{NR},{NS},{NT},{NU},{NV},{NW},{NX},{NY},{NZ},{OA},{OB},{OC},{OD},{OE},{OF},{OG},{OH},{OI},{OJ},{OK},{OL},{OM},{ON},{OO},{OP},{OQ},{OR},{OS},{OT},{OU},{OV},{OW},{OX},{OY},{OZ},{PA},{PB},{PC},{PD},{PE},{PF},{PG},{PH},{PI},{PJ},{PK},{PL},{PM},{PN},{PO},{PP},{PQ},{PR},{PS},{PT},{PU},{PV},{PW},{PX},{PY},{PZ},{QA},{QB},{QC},{QD},{QE},{QF},{QG},{QH},{QI},{QJ},{QK},{QL},{QM},{QN},{QO},{QP},{QQ},{QR},{QS},{QT},{QU},{QV},{QW},{QX},{QY},{QZ},{RA},{RB},{RC},{RD},{RE},{RF},{RG},{RH},{RI},{RJ},{RK},{RL},{RM},{RN},{RO},{RP},{RQ},{RR},{RS},{RT},{RU},{RV},{RW},{RX},{RY},{RZ},{SA},{SB},{SC},{SD},{SE},{SF},{SG},{SH},{SI},{SJ},{SK},{SL},{SM},{SN},{SO},{SP},{SQ},{SR},{SS},{ST},{SU},{SV},{SW},{SX},{SY},{SZ},{TA},{TB},{TC},{TD},{TE},{TF},{TG},{TH},{TI},{TJ},{TK},{TL},{TM},{TN},{TO},{TP},{TQ},{TR},{TS},{TT},{TU},{TV},{TW},{TX},{TY},{TZ},{UA},{UB},{UC},{UD},{UE},{UF},{UG},{UH},{UI},{UJ},{UK},{UL},{UM},{UN},{UO},{UP},{UQ},{UR},{UT},{UU},{UV},{UW},{UX},{UY},{UZ},{VA},{VB},{VC},{VD},{VE},{VF},{VG},{VH},{VI},{VJ},{VK},{VL},{VM},{VN},{VO},{VP},{VQ},{VR},{VS},{VT},{VU},{VV},{VW},{VX},{VY},{VZ},{WA},{WB},{WC},{WD},{WE},{WF},{WG},{WH},{WI},{WJ},{WK},{WL},{WM},{WN},{WO},{WP},{WQ},{WR},{WS},{WT},{WU},{WV},{WW},{WX},{WY},{WZ},{XA},{XB},{XC},{XD},{XE},{XF},{XG},{XH},{XI},{XJ},{XK},{XL},{XM},{XN},{XO},{XP},{XQ},{XR},{XS},{XT},{XU},{XV},{XW},{XX},{XY},{XZ},{YA},{YB},{YC},{YD},{YE},{YF},{YG},{YH},{YI},{YJ},{YK},{YL},{YM},{YN},{YO},{YP},{YQ},{YR},{YS},{YT},{YU},{YV},{YW},{YX},{YY},{YZ},{ZA},{ZB},{ZC},{ZD},{ZE},{ZF},{ZG},{ZH},{ZI},{ZJ},{ZK},{ZL},{ZM},{ZN},{ZO},{ZP},{ZQ},{ZR},{ZS},{ZT},{ZU},{ZV},{ZW},{ZX},{ZY},{ZZ},{??}" | sudo tee -a /etc/tor/torrc
echo StrictNodes 1 | sudo tee -a /etc/tor/torrc
As you will presumably notice, I Exclude ALL other possible two-letter codes {= 676 -- including ??, and leave out the one country that I wish to exit from {US}}. {That's only about twice as many as those in actual use [= 249], if the "User-assigned and Reserved" [+ 81] are included too [= 330]. It's that way because: it's much clearer that all are listed, and thus easier for anyone else to modify to suit their needs; it's also slightly future-proofed as codes come and go; it prevents an adversary from using those against Tor by claiming to be one of those "unused" codes.}
Then I enter systemctl restart tor which causes Tor to recognize the newly modified torrc, and to remove the circuits generated prior to the restart.
Thereafter, Tor will invariably build two US-exit circuits, as desired; BUT it will ALSO invariably build the next two exits in Europe. Then as I watch circuit usage, Tor doesn't seem to use those European circuits unless I access hidden services. Tor will then continue to build primarily US circuits, but seems to nearly-always keep at least a couple European ones open.
So it may be that Tor in fact is NOT using those circuits for the rest of my traffic.
When I first read what may be the relevant portion of the [manual, included below], {And I had read and noted [Roger Dingledine's comment]:
2 "(Re Sam's comment above, StrictNodes no longer applies to the ExitNodes config option. It only applies to excluding nodes.)" – Roger Dingledine Feb 8 '15 at 10:22}
I presumed that StrictNodes 1 would apply to ExcludeExitNodes as well as to ExcludeNodes. However, it now seems to me that Tor is behaving as if StrictNodes 1 DOES NOT APPLY to ExcludeExitNodes!
If that is currently the case, PLEASE switch it back! Users will retain much more anonymity, if they have to exit from a specific country, if Tor allows their circuits to merely exit in that specific country {by using ExcludeExitNodes} instead of forcing users who need to exit in a specific country to exclude ALL nodes outside that country {by using ExcludeNodes}. Or else choose to be tied to a specific exit by using .exit, which might limit anonymity more, and would also break https {I was told that by sigaint support, and that's a no-go for me}.
StrictNodes 0|1
If StrictNodes is set to 1, Tor will treat the ExcludeNodes option as a requirement to follow for all the circuits you generate, even if doing so will break functionality for you. If StrictNodes is set to 0, Tor will still try to avoid nodes in the ExcludeNodes list, but it will err on the side of avoiding unexpected errors. Specifically, StrictNodes 0 tells Tor that it is okay to use an excluded node when it is necessary to perform relay reachability self-tests, connect to a hidden service, provide a hidden service to a client, fulfill a .exit request, upload directory information, or download directory information. (Default: 0)
And when I reread again:
ExcludeExitNodes node,node,…
A list of identity fingerprints, country codes, and address patterns of nodes to never use when picking an exit node---that is, a node that delivers traffic for you outside the Tor network. Note that any node listed in ExcludeNodes is automatically considered to be part of this list too. See the ExcludeNodes option for more information on how to specify nodes. See also the caveats on the "ExitNodes" option below.
and:
ExitNodes node,node,…
A list of identity fingerprints, country codes, and address patterns of nodes to use as exit node---that is, a node that delivers traffic for you outside the Tor network. See the ExcludeNodes option for more information on how to specify nodes.
Note that if you list too few nodes here, or if you exclude too many exit nodes with ExcludeExitNodes, you can degrade functionality. For example, if none of the exits you list allows traffic on port 80 or 443, you won’t be able to browse the web.
Note also that not every circuit is used to deliver traffic outside of the Tor network. It is normal to see non-exit circuits (such as those used to connect to hidden services, those that do directory fetches, those used for relay reachability self-tests, and so on) that end at a non-exit node. To keep a node from being used entirely, see ExcludeNodes and StrictNodes.
The ExcludeNodes option overrides this option: any node listed in both ExitNodes and ExcludeNodes is treated as excluded.
The .exit address notation, if enabled via AllowDotExit, overrides this option.
It still seems to me that the behavior that I am seeing by Tor is NOT that which is described in the manual.
However if Tor actually ONLY uses the countries listed in "Onion Circuits" {which should have been excluded by ExcludeExitNodes} to build otherwise "NECESSARY" circuits, I would prefer hearing that from someone who knows that to be the case. And it would maybe be less painful to other noobs if the manual was updated accordingly so as to be very specific regarding ExcludeExitNodes.
Or maybe I've found a bug that should be reported??
P.S. There were six links above, but Stack Exchange does not allow noobs to write competently here. They state: "You need at least 10 reputation to post more than 2 links." I removed the last four.
