只大写第一个单词:

foo='one two three'
foo="${foo^}"
echo $foo

一二三

将变量中的每个单词大写:

foo="one two three"
foo=( $foo ) # without quotes
foo="${foo[@]^}"
echo $foo

一二三

(适用于bash 4+)

这里只是为了好玩:

foo="bar";    

echo $foo | awk '{$1=toupper(substr($1,0,1))substr($1,2)}1'
# or
echo ${foo^}
# or
echo $foo | head -c 1 | tr [a-z] [A-Z]; echo $foo | tail -c +2
# or
echo ${foo:1} | sed -e 's/^./\B&/'

Linux和OSX的另一种干净的解决方案，它也可以与bash变量一起使用

python -c "print(\"abc\".capitalize())"

返回美国广播公司

$ foo="bar";
$ foo=`echo ${foo:0:1} | tr  '[a-z]' '[A-Z]'`${foo:1}
$ echo $foo
Bar

下面是“原生”文本工具的使用方法:

#!/bin/bash

string="abcd"
first=`echo $string|cut -c1|tr [a-z] [A-Z]`
second=`echo $string|cut -c2-`
echo $first$second

它也可以在纯bash中使用bash-3.2完成:

# First, get the first character.
fl=${foo:0:1}

# Safety check: it must be a letter :).
if [[ ${fl} == [a-z] ]]; then
    # Now, obtain its octal value using printf (builtin).
    ord=$(printf '%o' "'${fl}")

    # Fun fact: [a-z] maps onto 0141..0172. [A-Z] is 0101..0132.
    # We can use decimal '- 40' to get the expected result!
    ord=$(( ord - 40 ))

    # Finally, map the new value back to a character.
    fl=$(printf '%b' '\'${ord})
fi

echo "${fl}${foo:1}"