[已解决]bash $temp

catalpa-bungei

Given a variable $temp, what is the effect of ${#temp} , ${temp%%word}, and ${temp/pattern/string}  ?

最佳答案

月排行榜 / 总排行榜

陶远航

2023-9-23 21:39:10

In Bash scripting, the expressions ${#temp}, ${temp%%word}, and ${temp/pattern/string} allow you to manipulate the value of the variable $temp in different ways.

1. ${#temp}: This expression returns the length of the value stored in the variable $temp. For example, if $temp contains the string "Hello", ${#temp} will evaluate to 5.

2. ${temp%%word}: This expression removes the longest matching suffix pattern "word" from the value of $temp. It returns the resulting string after removing the suffix. For example, if $temp contains the string "/path/to/file.txt", ${temp%%/*} will remove "/path" and return "to/file.txt". This is known as "parameter expansion".

3. ${temp/pattern/string}: This expression performs pattern substitution within the value of $temp. It replaces the first occurrence of the pattern with the given string. For example, if $temp contains the string "Hello, world!", ${temp/o/0} will replace the first 'o' character with '0' and return "Hell0, world!". If you want to replace all occurrences of the pattern, you can use ${temp//o/0}. Again, this is a form of "parameter expansion".

These expressions are powerful tools in Bash for manipulating string variables and performing operations like length calculation, pattern matching, and substitution.
如果问题已经解决，请设置最佳答案

跳转到最佳答案楼层

isdkz

1. ${#temp}：返回变量 $temp 的长度。
2. ${temp%%word}：从变量 $temp 的末尾开始，删除最长匹配的字符串 "word"，并返回剩余的字符串。
3. ${temp/pattern/string}：将变量 $temp 中第一个匹配 "pattern" 的字符串替换为 "string"，并返回替换后的字符串。如果使用 /g 选项，则会替换所有匹配的字符串。

举个例子：

假设 $temp 的值为 "hello world"。

1. ${#temp} 的结果为 11，因为 "hello world" 这个字符串的长度为 11。
2. ${temp%%world} 的结果为 "hello "，因为从变量 $temp 的末尾开始，最长匹配的字符串是 "world"，所以删除了 "world"，并返回剩余的字符串 "hello "。
3. ${temp/o/a} 的结果为 "hello warld"，因为它将第一个匹配 "o" 的字符替换为 "a"，并返回替换后的字符串 "hello warld"。

陶远航

In Bash scripting, the expressions ${#temp}, ${temp%%word}, and ${temp/pattern/string} allow you to manipulate the value of the variable $temp in different ways.

1. ${#temp}: This expression returns the length of the value stored in the variable $temp. For example, if $temp contains the string "Hello", ${#temp} will evaluate to 5.

2. ${temp%%word}: This expression removes the longest matching suffix pattern "word" from the value of $temp. It returns the resulting string after removing the suffix. For example, if $temp contains the string "/path/to/file.txt", ${temp%%/*} will remove "/path" and return "to/file.txt". This is known as "parameter expansion".

3. ${temp/pattern/string}: This expression performs pattern substitution within the value of $temp. It replaces the first occurrence of the pattern with the given string. For example, if $temp contains the string "Hello, world!", ${temp/o/0} will replace the first 'o' character with '0' and return "Hell0, world!". If you want to replace all occurrences of the pattern, you can use ${temp//o/0}. Again, this is a form of "parameter expansion".

These expressions are powerful tools in Bash for manipulating string variables and performing operations like length calculation, pattern matching, and substitution.
如果问题已经解决，请设置最佳答案

Mike_python小

${#temp}: 这个表达式获取了变量 $temp 的长度，即字符串的字符个数。例如，如果 $temp 的值为 "Hello"，那么 ${#temp} 将会返回 5。

${temp%%word}: 这个表达式从变量 $temp 的末尾开始匹配并删除最长的匹配项 "word"。其中 %% 表示删除后缀。例如，如果 $temp 的值为 "HelloWorld"，而 "World" 是要删除的子字符串，那么 ${temp%%World} 将会返回 "Hello"。

${temp/pattern/string}: 这个表达式将变量 $temp 中第一个匹配 pattern 的子字符串替换为 string。其中 / 是替换操作符。如果 pattern 匹配多个子字符串，则只替换第一个匹配项。例如，如果 $temp 的值为 "HelloWorld"，而我们想把 "World" 替换为 "Universe"，那么 ${temp/World/Universe} 将会返回 "HelloUniverse"。

需要注意的是，这些表达式都是针对字符串操作的，可以用于处理变量中存储的文本内容。另外，这些表达式支持使用通配符进行模式匹配，可以更灵活地应用于字符串处理。

球一个最佳答案谢谢啦！这对我非常重要！
回答可能有误，多多谅解！

Mike_python小

陶远航 发表于 2023-9-23 18:39
In Bash scripting, the expressions ${#temp}, ${temp%%word}, and ${temp/pattern/string} allow you to  ...

我嘞个豆，英格雷是