使用 Bash 计算字符串中字符的出现次数
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Count occurrences of a char in a string using Bash
提问by Jericob
I need to count the number of occurrences of a char in a stringusing Bash.
我需要使用 Bash 计算字符串中某个字符的出现次数。
In the following example, when the char is (for example) t, it echosthe correct number of occurrences of tin var, but when the character is comma or semicolon, it prints out zero:
在下面的示例中，当字符是（例如）t，它echoš出现的正确的号码t中var，但是当字符是逗号或分号，它打印出零：
var = "text,text,text,text"
num = `expr match $var [,]`
echo "$num"
采纳答案by hek2mgl
I would use the following awkcommand:
我会使用以下awk命令：
string="text,text,text,text"
char=","
awk -F"${char}" '{print NF-1}' <<< "${string}"
I'm splitting the string by $charand print the number of resulting fields minus 1.
我正在拆分字符串$char并打印结果字段的数量减去 1。
If your shell does not support the <<<operator, use echo:
如果您的 shell 不支持该<<<运算符，请使用echo：
echo "${string}" | awk -F"${char}" '{print NF-1}'
回答by jm666
you can for example remove all other chars and count the whats remains, like:
例如，您可以删除所有其他字符并计算剩余的内容，例如：
var="text,text,text,text"
res="${var//[^,]}"
echo "$res"
echo "${#res}"
will print
将打印
,,,
3
or
或者
tr -dc ',' <<<"$var" | awk '{ print length; }'
or
或者
tr -dc ',' <<<"$var" | wc -c #works, but i don't like wc.. ;)
or
或者
awk -F, '{print NF-1}' <<<"$var"
or
或者
grep -o ',' <<<"$var" | grep -c .
or
或者
perl -nle 'print s/,//g' <<<"$var"
回答by Robin Hsu
You can do it by combining trand wccommands. For example, to count ein the string referee
您可以通过组合tr和wc命令来完成。例如，e在字符串中 计数referee
echo "referee" | tr -cd 'e' | wc -c
output
输出
4
Explanations: Command tr -cd 'e'removes all characters other than 'e', and Command wc -ccounts the remaining characters.
说明：Commandtr -cd 'e'删除除 'e' 以外的所有字符，Commandwc -c计算剩余字符数。
Multiple lines of input are also good for this solution, like command cat mytext.txt | tr -cd 'e' | wc -ccan counts ein the file mytext.txt, even thought the file may contain many lines.
多行输入也适用于该解决方案，例如命令cat mytext.txt | tr -cd 'e' | wc -c可以e在文件中计数mytext.txt，甚至认为文件可能包含多行。
回答by rmanna
Building on everyone's great answers and comments, this is the shortest and sweetest version:
基于每个人的精彩回答和评论，这是最短和最甜蜜的版本：
grep -o "$needle" <<< "$haystack" | wc -l
grep -o "$needle" <<< "$haystack" | wc -l
回答by user2508516
awk works well if you your server has it
如果你的服务器有 awk，它运行良好
var="text,text,text,text"
num=$(echo "${var}" | awk -F, '{print NF-1}')
echo "${num}"
回答by Freeman
also check this out, for example we wanna count t
也检查一下，例如我们想要数 t
echo "test" | awk -v RS='t' 'END{print NR-1}'
or in python
或在 python
python -c 'print "this is for test".count("t")'
or even better, we can make our script dynamic with awk
甚至更好，我们可以使我们的脚本动态 awk
echo 'test' | awk '{for (i=1 ; i<=NF ; i++) array[$i]++ } END{ for (char in array) print char,array[char]}' FS=""
in this case output is like this :
在这种情况下，输出是这样的：
e 1
s 1
t 2
回答by Mathew P V
I Would suggest the following:
我建议如下：
var="any given string"
N=${#var}
G=${var//g/}
G=${#G}
(( G = N - G ))
echo "$G"
No call to any other program
不调用任何其他程序
