sort -u -t, -k1,1 file
-u
为了独特-t,
所以逗号是定界符-k1,1
对于关键字段1
测试结果:
overflow@domain2.com,2009-11-27 00:58:29.793000000,xx3.net,255.255.255.0 stack2@domain.com,2009-11-27 01:05:47.893000000,xx2.net,127.0.0.1

sort -u -t, -k1,1 file
-u为了独特
-t,所以逗号是定界符
-k1,1对于关键字段1
测试结果:
overflow@domain2.com,2009-11-27 00:58:29.793000000,xx3.net,255.255.255.0 stack2@domain.com,2009-11-27 01:05:47.893000000,xx2.net,127.0.0.1