替换字符串，如果第一个字母使用SED

Question

我尝试使用到SED答案写这个问题Edit a file using sed/awk大写：

sed -e 's/^[A-Z]/$:$&/' file.txt 

但结果是：

wednesday 
$:$Weekday 

$:$thursday 
$:$Weekday 

$:$friday 
$:$Weekday 

$:$saturday 
$:$MaybeNot 

$:$sunday 
$:$MaybeNot 

$:$monday 
$:$Weekday 

$:$tuesday 
$:$Weekday 

为什么更换，如果第一个字符是小写？

Answer 1

这是根据this bug report根据区域中意外字符排序引起的“特征”，进一步解释为here和here。

$ locale 
LANG=en_GB.UTF-8 
LC_CTYPE="en_GB.UTF-8" 
LC_NUMERIC="en_GB.UTF-8" 
LC_TIME="en_GB.UTF-8" 
LC_COLLATE="en_GB.UTF-8" 
LC_MONETARY="en_GB.UTF-8" 
LC_MESSAGES="en_GB.UTF-8" 
LC_ALL= 

$ echo "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" | sed -e 's/[A-Z]/./g' 
..........................a......................... 

$ echo "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" | sed -e 's/[a-z]/./g' 
.........................Z.......................... 

$ echo "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" | LC_ALL=C sed -e 's/[A-Z]/./g' 
..........................abcdefghijklmnopqrstuvwxyz 

$ echo "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" | LC_ALL=C sed -e 's/[a-z]/./g' 
ABCDEFGHIJKLMNOPQRSTUVWXYZ.......................... 

$ echo "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" | sed -e 's/[[:upper:]]/./g' 
..........................abcdefghijklmnopqrstuvwxyz 

$ echo "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" | sed -e 's/[[:lower:]]/./g' 
ABCDEFGHIJKLMNOPQRSTUVWXYZ.......................... 

$ sed --version 
GNU sed version 4.2.1