Linux Bash：如何标记字符串变量？
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Bash: How to tokenize a string variable?
提问by Jake Wilson
If I have a string variable who's value is "john is 17 years old"how do I tokenize this using spaces as the delimeter? Would I use awk?
如果我有一个字符串变量，其值是"john is 17 years old"如何使用空格作为分隔符来标记它？我会用awk吗？
采纳答案by John Kugelman
Use the shell's automatic tokenization of unquoted variables:
使用 shell 对未加引号变量的自动标记化：
$ string="john is 17 years old"
$ for word in $string; do echo "$word"; done
john
is
17
years
old
If you want to change the delimiter you can set the $IFSvariable, which stands for internal field separator. The default value of $IFSis " \t\n"(space, tab, newline).
如果要更改分隔符，可以设置$IFS变量，它代表内部字段分隔符。的默认值$IFS是" \t\n"（空格，制表，换行）。
$ string="john_is_17_years_old"
$ (IFS='_'; for word in $string; do echo "$word"; done)
john
is
17
years
old
(Note that in this second example I added parentheses around the second line. This creates a sub-shell so that the change to $IFSdoesn't persist. You generally don't want to permanently change $IFSas it can wreak havoc on unsuspecting shell commands.)
（请注意，在第二个示例中，我在第二行周围添加了括号。这会创建一个子 shell，以便更改$IFS不会持续存在。您通常不希望永久更改，$IFS因为它可能会对毫无戒心的 shell 命令造成严重破坏。 )
回答by harshit
you can try something like this :
你可以尝试这样的事情：
#!/bin/bash
n=0
a=/home/file.txt
for i in `cat ${a} | tr ' ' '\n'` ; do
str=${str},${i}
let n=$n+1
var=`echo "var${n}"`
echo $var is ... ${i}
done
回答by Diego Torres Milano
$ string="john is 17 years old"
$ tokens=( $string )
$ echo ${tokens[*]}
For other delimiters, like ';'
对于其他分隔符，如“;”
$ string="john;is;17;years;old"
$ IFS=';' tokens=( $string )
$ echo ${tokens[*]}
回答by kurumi
$ string="john is 17 years old"
$ set -- $string
$ echo
john
$ echo
is
$ echo
17
回答by Mila Nautikus
with POSIX extended regex:
使用 POSIX 扩展正则表达式：
$ str='a b c d'
$ echo "$str" | sed -E 's/\W+/\n/g' | hexdump -C
00000000 61 0a 62 0a 63 0a 64 0a |a.b.c.d.|
00000008
this is like python's re.split(r'\W+', str)
这就像蟒蛇的 re.split(r'\W+', str)
\Wmatches a non-word character,
including space, tab, newline, return, [like the bash fortokenizer]
but also including symbols like quotes, brackets, signs, ...
\W匹配非单词字符，
包括空格、制表符、换行符、回车符、[如bash for标记器]，
但也包括引号、括号、符号等符号...
... except the underscore sign _,
so snake_caseis one word, but kebab-caseare two words.
......除了下划线符号_，
所以snake_case是一字之差，却kebab-case是两个词。
leading and trailing space will create an empty line.
前导和尾随空格将创建一个空行。
