1、找一个文件，内容中包含大小写，用这个文件作为演示样例。这里使用.bash_profile文件复制为bash_profile1作为演示文件。
2、查看bash_profile文件的内容，里面包含大小写字母
3、下面用bash_profile1文件作为样例介绍将大写字母转换为小写字母
4、命令语法是tr+‘文件中原有的字符’ ‘要替换成的字符’< 要替换的文件名这里具体的命令就是tr 'A-Z' 刻八圄俏9;a-z' <./bash_profile1'A-Z' 是替换前文件中的字符'a-z'是替换后文件中的字符./bash_profile1 是要替换的文件名
5、这里看到转换后，都是小写字母了
6、如果以上经验帮到您，麻烦在左下角给点个赞，谢谢！
7、可以使用命令tr 'a-z' 'A-Z'<./bash_profile1 将当前目录下的bash_profile1文件中的所有小写字母，转换成大写字母。
8、下面是tr命令的manual，you can read it for reference.TR(1) User Commands TR(1)NAME tr - translate or delete charactersSYNOPSIS tr [OPTION]... SET1 [SET2]DESCRIPTION Translate, squeeze, and/or delete characters from standard input, writ- ing to standard output. -c, -C, --complement use the complement of SET1 -d, --delete delete characters in SET1, do not translate -s, --squeeze-repeats replace each input sequence of a repeated character that is listed in SET1 with a single occurrence of that character -t, --truncate-set1 first truncate SET1 to length of SET2 --help display this help and exit --version output version information and exit SETs are specified as strings of characters. Most represent them- selves. Interpreted sequences are: \NNN character with octal value NNN (1 to 3 octal digits) \\ backslash \a audible BEL \b backspace \f form feed \n new line \r return \t horizontal tab \v vertical tab CHAR1-CHAR2 all characters from CHAR1 to CHAR2 in ascending order [CHAR*] in SET2, copies of CHAR until length of SET1 [CHAR*REPEAT] REPEAT copies of CHAR, REPEAT octal if starting with 0 [:alnum:] all letters and digits [:alpha:] all letters [:blank:] all horizontal whitespace [:cntrl:] all control characters [:digit:] all digits [:graph:] all printable characters, not including space [:lower:] all lower case letters [:print:] all printable characters, including space [:punct:] all punctuation characters [:space:] all horizontal or vertical whitespace [:upper:] all upper case letters [:xdigit:] all hexadecimal digits [=CHAR=] all characters which are equivalent to CHAR Translation occurs if -d is not given and both SET1 and SET2 appear. -t may be used only when translating. SET2 is extended to length of SET1 by repeating its last character as necessary. Excess characters of SET2 are ignored. Only [:lower:] and [:upper:] are guaranteed to expand in ascending order; used in SET2 while translating, they may only be used in pairs to specify case conversion. -s uses SET1 if not translating nor deleting; else squeezing uses SET2 and occurs after translation or deletion.AUTHOR Written by Jim Meyering.REPORTING BUGS Report tr bugs to [email protected] GNU coreutils home page: <http://www.gnu.org/software/coreutils/> General help using GNU software: <http://www.gnu.org/gethelp/> Report tr translation bugs to <http://translationproject.org/team/>COPYRIGHT Copyright © 2010 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.SEE ALSO The full documentation for tr is maintained as a Texinfo manual. If the info and tr programs are properly installed at your site, the com- mand info coreutils 'tr invocation' should give you access to the complete manual.GNU coreutils 8.4 June 2010 TR(1)