bash中有没有将字符串转换为小写字符串的方法?

例如,如果我有:

a="Hi all"

我想将其转换为:

"hi all"

当前回答

将转换后的字符串存储到变量中。跟踪对我有用-$SOURCE_NAME至$TARGET_NAME

TARGET_NAME="`echo $SOURCE_NAME | tr '[:upper:]' '[:lower:]'`"

其他回答

如果使用v4,则会进行烘焙。如果不是,这里有一个简单、广泛适用的解决方案。这个线程上的其他答案(和注释)对创建下面的代码非常有用。

# Like echo, but converts to lowercase
echolcase () {
    tr [:upper:] [:lower:] <<< "${*}"
}

# Takes one arg by reference (var name) and makes it lowercase
lcase () { 
    eval "${1}"=\'$(echo ${!1//\'/"'\''"} | tr [:upper:] [:lower:] )\'
}

笔记:

执行:a=“Hi All”,然后:lcase a将执行与:a=$相同的操作(echolcase“Hi All”)在lcase函数中,使用${!1//\'/“'\'”}而不是${!1},即使字符串有引号,也可以使用此函数。

使用此命令执行同样的操作,它会将大写字符串转换为小写:

sed 's/[A-Z]/[a-z]/g' <filename>

在zsh中:

echo $a:u

我爱你!

你可以试试这个

s="Hello World!" 

echo $s  # Hello World!

a=${s,,}
echo $a  # hello world!

b=${s^^}
echo $b  # HELLO WORLD!

裁判:http://wiki.workassis.com/shell-script-convert-text-to-lowercase-and-uppercase/

在Bash 4中:

小写

$ string="A FEW WORDS"
$ echo "${string,}"
a FEW WORDS
$ echo "${string,,}"
a few words
$ echo "${string,,[AEIUO]}"
a FeW WoRDS

$ string="A Few Words"
$ declare -l string
$ string=$string; echo "$string"
a few words

大写

$ string="a few words"
$ echo "${string^}"
A few words
$ echo "${string^^}"
A FEW WORDS
$ echo "${string^^[aeiou]}"
A fEw wOrds

$ string="A Few Words"
$ declare -u string
$ string=$string; echo "$string"
A FEW WORDS

切换(未记录,但可在编译时配置)

$ string="A Few Words"
$ echo "${string~~}"
a fEW wORDS
$ string="A FEW WORDS"
$ echo "${string~}"
a FEW WORDS
$ string="a few words"
$ echo "${string~}"
A few words

大写(未记录,但可在编译时配置)

$ string="a few words"
$ declare -c string
$ string=$string
$ echo "$string"
A few words

标题大小写:

$ string="a few words"
$ string=($string)
$ string="${string[@]^}"
$ echo "$string"
A Few Words

$ declare -c string
$ string=(a few words)
$ echo "${string[@]}"
A Few Words

$ string="a FeW WOrdS"
$ string=${string,,}
$ string=${string~}
$ echo "$string"
A few words

要关闭声明属性,请使用+。例如,声明+c字符串。这会影响后续赋值,而不是当前值。

declare选项更改变量的属性,但不更改内容。示例中的重新分配会更新内容以显示更改。

编辑:

按照ghostdog74的建议,添加了“按单词切换第一个字符”(${var~})。

编辑:更正波浪号行为以匹配Bash 4.3。