Below, I will show you how to create tac-pac (similar to show tech-support in IOS) file in Cisco NX-OS:

Step 1.  Check the TAC-PAC in user mode

SH-N7K-01# tac-pac ?

bootflash:  Select destination filesystem
ftp:        Select destination filesystem
logflash:   Select destination filesystem
scp:        Select destination filesystem
sftp:       Select destination filesystem
slot0:      Select destination filesystem
tftp:       Select destination filesystem
volatile:   Select destination filesystem

Step 2.  Saving the TAC-PAC in bootflash:

SH-N7K-01# tac-pac bootflash:
Show tech details will take  4-6 minutes to complete. Please Wait …
Checking the TAC-PAC file save in bootflash.

SH-N7K-01# dir bootflash:
0    Oct 18 10:42:23 2014  20141018_024223_poap_7369_init.log
890    Oct 18 10:59:18 2014  20141018_025902_poap_7268_init.log
0    Nov 07 11:48:42 2014  20141107_034842_poap_7187_init.log
7062    Mar 27 19:00:36 2015  P@ssw0rd123
10816437    Jul 21 09:30:38 2015  en
10813113    Jul 21 09:42:36 2015  ftp
510    Oct 18 10:51:42 2014  license_JAF1817AMJH_36.lic
16384    Oct 18 10:33:55 2014  lost+found/
420778741    Oct 18 10:35:23 2014  n7000-s2-dk9.6.2.8a.bin
36619776    Oct 18 10:34:30 2014  n7000-s2-kickstart.6.2.8a.bin
4096    Oct 18 10:39:52 2014  scripts/
   10849256    Jul 21 09:46:26 2015  show_tech_out.gz   <<<<<< shows the save tac-pac
4096    Nov 25 23:08:12 2014  vdc_2/
4096    Oct 18 10:38:56 2014  vdc_3/
4096    Oct 18 10:38:56 2014  vdc_4/
4096    Oct 18 10:38:56 2014  vdc_5/
2584    Nov 28 19:14:48 2014  vlan.dat
Usage for bootflash://sup-local   <<<<<<< TAC-File is save in sup-local
616329216 bytes used
1200156672 bytes free
1816485888 bytes total

Step 3. Copy the tac-pac file via tftp. In this scenario, I have used a TFTP32 client which I run on my machine with IP address 172.17.112.76.

SH-N7K-01# copy bootflash://sup-local/show_tech_out.gz tftp://172.17.112.76 vrf management

Trying to connect to tftp server……
Connection to Server Established.
[############             ]         3.40MB  s

TAC-PAC file is copied below via TFTP client to my machine.