Sorting in VIM (version 7)

:[range]sor[t][!] [i][u][r][n][x][o] [/{pattern}/]

Examples

document content:

150
  20
xavier
300
Ace
1205
710
aab
300
20
1205

sort alphabetic, case sensitive:

:sort

  20
1205
1205
150
20
300
300
710
Ace  <-- notice capital A is before a
aab
xavier

sort alphabetic, case-insensitive:

:sort i

  20
1205
1205
150
20
300
300
710
aab  <-- notice lowercase a is before A
Ace
xavier

sort unique:

:sort u

  20
1205  <-- duplicate has been removed
150
20
300  <-- duplicate has been removed
710
Ace  <-- capital A is before a
aab
xavier

sort unique and case insensitive:

:sort ui

  20
1205  <-- duplicate has been removed
150
20
300  <-- duplicate has been removed
710
aab  <-- lowercase a is before A
Ace
xavier

sort numeric:

:sort n

xavier
Ace
aab
  20
20
150
300
300
710
1205
1205