90. GAWK 字符串函数
tolower 和 toupper 仅在 Gawk 中可用。
顾名思义，该函数将给定的字符串转换为小写或大写，如下所示。
$ awk '{print tolower($0)}' items.txt
101,hd camcorder,video,210,10
102,refrigerator,appliance,850,2
103,mp3 player,audio,270,15
104,tennis racket,sports,190,20
105,laser printer,office,475,5
$ awk '{print toupper($0)}' items.txt
101,HD CAMCORDER,VIDEO,210,10
102,REFRIGERATOR,APPLIANCE,850,2
103,MP3 PLAYER,AUDIO,270,15
104,TENNIS RACKET,SPORTS,190,20
105,LASER PRINTER,OFFICE,475,5
