这完全可以用bash字符串操作完成:

first="I love Suzy and Mary"
second="Sara"
first=${first/Suzy/$second}

这只会取代第一个事件;要将它们全部替换，请将第一个斜杠加倍:

first="Suzy, Suzy, Suzy"
second="Sara"
first=${first//Suzy/$second}
# first is now "Sara, Sara, Sara"

对于Dash，之前的所有帖子都不起作用

POSIX sh兼容的解决方案是:

result=$(echo "$firstString" | sed "s/Suzi/$secondString/")

这将替换每一行输入中的第一个出现的位置。添加/g标记替换所有出现的情况:

result=$(echo "$firstString" | sed "s/Suzi/$secondString/g")

如果明天你决定不再爱她，她也可以被取代:

today=$(</tmp/lovers.txt)
tomorrow="${today//Suzi/Sara}"
echo "${tomorrow//Marry/Jesica}" > /tmp/lovers.txt

离开爱人，一定有50种方法。

使用AWK:

firstString="I love Suzi and Marry"
echo "$firstString" | awk '{gsub("Suzi","Sara"); print}'

纯POSIX shell方法，与Roman Kazanovskyi基于sed的答案不同，它不需要外部工具，只需要shell自己的本地参数展开。注意，长文件名被最小化，所以代码更适合一行:

f="I love Suzi and Marry"
s=Sara
t=Suzi
[ "${f%$t*}" != "$f" ] && f="${f%$t*}$s${f#*$t}"
echo "$f"

输出:

I love Sara and Marry

工作原理:

Remove Smallest Suffix Pattern. "${f%$t*}" returns "I love" if the suffix $t "Suzi*" is in $f "I love Suzi and Marry". But if t=Zelda, then "${f%$t*}" deletes nothing, and returns the whole string "I love Suzi and Marry". This is used to test if $t is in $f with [ "${f%$t*}" != "$f" ] which will evaluate to true if the $f string contains "Suzi*" and false if not. If the test returns true, construct the desired string using Remove Smallest Suffix Pattern ${f%$t*} "I love" and Remove Smallest Prefix Pattern ${f#*$t} "and Marry", with the 2nd string $s "Sara" in between.

我认为这是你用例中最简洁的形式:

firstString="${firstString//Suzi/$secondString}"