/etc/localtime

/etc/localtime configures the system-wide timezone of the local system. It may be link to /usr/share/zoneinfo/ followed by a timezone identifier such as "Europe/Berlin" or "Etc/UTC" pointing to binary tzfile(5) timezone data for the configured timezone.

Timezone identifier is extracted from the target name of /etc/localtime,

The timezone may be overridden for individual programs by using the $TZ . See environ(7).

timedatectl(1) changes this file during runtime.
systemd-firstboot(1) to initialize the time zone on mounted (but not booted) system images.

-rw-r--r-- 1 root root 3519 Nov  5 14:00 localtime
 >hexdump -C localtime
000  54 5a 69 66 32 00 00 00  00 00 00 00 00 00 00 00  |TZif2...........|
010  00 00 00 00 00 00 00 04  00 00 00 04 00 00 00 00  |................|
020  00 00 00 eb 00 00 00 04  00 00 00 10 9e a6 1e 70  |...............p|
030  9f ba eb 60 a0 86 00 70  a1 9a cd 60 a2 65 e2 70  |...`...p...`.e.p|
040  a3 83 e9 e0 a4 6a ae 70  a5 35 a7 60 a6 53 ca f0  |.....j.p.5.`.S..|
050  a7 15 89 60 a8 33 ac f0  a8 fe a5 e0 aa 13 8e f0  |...`.3..........|
060  aa de 87 e0 ab f3 70 f0  ac be 69 e0 ad d3 52 f0  |......p...i...R.|
070  ae 9e 4b e0 af b3 34 f0  b0 7e 2d e0 b1 9c 51 70  |..K...4..~-...Qp|
080  b2 67 4a 60 b3 7c 33 70  b4 47 2c 60 b5 5c 15 70  |.gJ`.|3p.G,`.\.p|
090  b6 27 0e 60 b7 3b f7 70  b8 06 f0 60 b9 1b d9 70  |.'.`.;.p...`...p|
0a0  b9 e6 d2 60 bb 04 f5 f0  bb c6 b4 60 bc e4 d7 f0  |...`.......`....|
0b0  bd af d0 e0 be c4 b9 f0  bf 8f b2 e0 c0 a4 9b f0  |................|
0c0  c1 6f 94 e0 c2 84 7d f0  c3 4f 76 e0 c4 64 5f f0  |.o....}..Ov..d_.|
0d0  c5 2f 58 e0 c6 4d 7c 70  c7 0f 3a e0 c8 2d 5e 70  |./X..M|p..:..-^p|
0e0  c8 f8 57 60 ca 0d 40 70  ca d8 39 60 cb 88 f0 70  |..W`..@p..9`...p|
0f0  d2 23 f4 70 d2 60 fb e0  d3 75 e4 f0 d4 40 dd e0  |.#.p.`...u...@..|
100  d5 55 c6 f0 d6 20 bf e0  d7 35 a8 f0 d8 00 a1 e0  |.U... ...5......|
110  d9 15 8a f0 d9 e0 83 e0  da fe a7 70 db c0 65 e0  |...........p..e.|
120  dc de 89 70 dd a9 82 60  de be 6b 70 df 89 64 60  |...p...`..kp..d`|
130  e0 9e 4d 70 e1 69 46 60  e2 7e 2f 70 e3 49 28 60  |..Mp.iF`.~/p.I(`|
140  e4 5e 11 70 e5 57 2e e0  e6 47 2d f0 e7 37 10 e0  |.^.p.W...G-..7..|
150  e8 27 0f f0 e9 16 f2 e0  ea 06 f1 f0 ea f6 d4 e0  |.'..............|
160  eb e6 d3 f0 ec d6 b6 e0  ed c6 b5 f0 ee bf d3 60  |...............`|
170  ef af d2 70 f0 9f b5 60  f1 8f b4 70 f2 7f 97 60  |...p...`...p...`|
180  f3 6f 96 70 f4 5f 79 60  f5 4f 78 70 f6 3f 5b 60  |.o.p._y`.Oxp.?[`|
190  f7 2f 5a 70 f8 28 77 e0  f9 0f 3c 70 fa 08 59 e0  |./Zp.(w.....p?.b.@o.pA..`|
2d0  42 4f 94 70 43 64 61 60  44 2f 76 70 45 44 43 60  |BO.pCda`D/vpEDC`|
2e0  45 f3 a8 f0 47 2d 5f e0  47 d3 8a f0 49 0d 41 e0  |E...G-_.G...I.A.|
2f0  49 b3 6c f0 4a ed 23 e0  4b 9c 89 70 4c d6 40 60  |I.l.J.#.K..pL.@`|
300  4d 7c 6b 70 4e b6 22 60  4f 5c 4d 70 50 96 04 60  |M|kpN."`O\MpP..`|
310  51 3c 2f 70 52 75 e6 60  53 1c 11 70 54 55 c8 60  |Q..p....?.b..|
a60  00 00 00 40 6f b2 70 00  00 00 00 41 84 7f 60 00  |...@o.p....A..`.|
a70  00 00 00 42 4f 94 70 00  00 00 00 43 64 61 60 00  |...BO.p....Cda`.|
a80  00 00 00 44 2f 76 70 00  00 00 00 45 44 43 60 00  |...D/vp....EDC`.|
a90  00 00 00 45 f3 a8 f0 00  00 00 00 47 2d 5f e0 00  |...E.......G-_..|
aa0  00 00 00 47 d3 8a f0 00  00 00 00 49 0d 41 e0 00  |...G.......I.A..|
ab0  00 00 00 49 b3 6c f0 00  00 00 00 4a ed 23 e0 00  |...I.l.....J.#..|
ac0  00 00 00 4b 9c 89 70 00  00 00 00 4c d6 40 60 00  |...K..p....L.@`.|
ad0  00 00 00 4d 7c 6b 70 00  00 00 00 4e b6 22 60 00  |...M|kp....N."`.|
ae0  00 00 00 4f 5c 4d 70 00  00 00 00 50 96 04 60 00  |...O\Mp....P..`.|
af0  00 00 00 51 3c 2f 70 00  00 00 00 52 75 e6 60 00  |...Q</p....Ru.`.|
b00  00 00 00 53 1c 11 70 00  00 00 00 54 55 c8 60 00  |...S..p....TU.`.|
b10  00 00 00 54 fb f3 70 00  00 00 00 56 35 aa 60 00  |...T..p....V5.`.|
b20  00 00 00 56 e5 0f f0 00  00 00 00 58 1e c6 e0 00  |...V.......X....|
b30  00 00 00 58 c4 f1 f0 00  00 00 00 59 fe a8 e0 00  |...X.......Y....|
b40  00 00 00 5a a4 d3 f0 00  00 00 00 5b de 8a e0 00  |...Z.......[....|
b50  00 00 00 5c 84 b5 f0 00  00 00 00 5d be 6c e0 00  |...\.......].l..|
b60  00 00 00 5e 64 97 f0 00  00 00 00 5f 9e 4e e0 00  |...^d......_.N..|
b70  00 00 00 60 4d b4 70 00  00 00 00 61 87 6b 60 00  |...`M.p....a.k`.|
b80  00 00 00 62 2d 96 70 00  00 00 00 63 67 4d 60 00  |...b-.p....cgM`.|
b90  00 00 00 64 0d 78 70 00  00 00 00 65 47 2f 60 00  |...d.xp....eG/`.|
ba0  00 00 00 65 ed 5a 70 00  00 00 00 67 27 11 60 00  |...e.Zp....g'.`.|
bb0  00 00 00 67 cd 3c 70 00  00 00 00 69 06 f3 60 00  |...g.<p....i..`.|
bc0  00 00 00 69 ad 1e 70 00  00 00 00 6a e6 d5 60 00  |...i..p....j..`.|
bd0  00 00 00 6b 96 3a f0 00  00 00 00 6c cf f1 e0 00  |...k.:.....l....|
be0  00 00 00 6d 76 1c f0 00  00 00 00 6e af d3 e0 00  |...mv......n....|
bf0  00 00 00 6f 55 fe f0 00  00 00 00 70 8f b5 e0 00  |...oU......p....|
c00  00 00 00 71 35 e0 f0 00  00 00 00 72 6f 97 e0 00  |...q5......ro...|
c10  00 00 00 73 15 c2 f0 00  00 00 00 74 4f 79 e0 00  |...s.......tOy..|
c20  00 00 00 74 fe df 70 00  00 00 00 76 38 96 60 00  |...t..p....v8.`.|
c30  00 00 00 76 de c1 70 00  00 00 00 78 18 78 60 00  |...v..p....x.x`.|
c40  00 00 00 78 be a3 70 00  00 00 00 79 f8 5a 60 00  |...x..p....y.Z`.|
c50  00 00 00 7a 9e 85 70 00  00 00 00 7b d8 3c 60 00  |...z..p....{.<`.|
c60  00 00 00 7c 7e 67 70 00  00 00 00 7d b8 1e 60 00  |...|~gp....}..`.|
c70  00 00 00 7e 5e 49 70 00  00 00 00 7f 98 00 60 02  |...~^Ip.......`.|
c80  01 02 01 02 01 02 01 02  01 02 01 02 01 02 01 02  |................|
*
cb0  03 04 02 01 02 01 02 01  02 01 02 01 02 01 02 01  |................|
cc0  02 01 02 01 02 01 02 01  02 01 02 01 02 01 02 01  |................|
*
d60  02 01 02 01 02 01 02 01  02 01 02 ff ff ba 9e 00  |................|
d70  00 ff ff c7 c0 01 04 ff  ff b9 b0 00 08 ff ff c7  |................|
d80  c0 01 0c ff ff c7 c0 01  10 4c 4d 54 00 45 44 54  |.........LMT.EDT|
d90  00 45 53 54 00 45 57 54  00 45 50 54 00 00 00 00  |.EST.EWT.EPT....|
da0  00 01 00 00 00 00 01 0a  45 53 54 35 45 44 54 2c  |........EST5EDT,|
db0  4d 33 2e 32 2e 30 2c 4d  31 31 2e 31 2e 30 0a     |M3.2.0,M11.1.0.|