我在Bash中有一个字符串:

string="My string"

如何测试它是否包含另一个字符串?

if [ $string ?? 'foo' ]; then
  echo "It's there!"
fi

哪里是我不认识的接线员。我使用echo和grep吗?

if echo "$string" | grep 'foo'; then
  echo "It's there!"
fi

这看起来有点笨拙。


当前回答

grep-q对于这个目的很有用。

同样使用awk:

string="unix-bash 2389"
character="@"
printf '%s' "$string" | awk -vc="$character" '{ if (gsub(c, "")) { print "Found" } else { print "Not Found" } }'

输出:

未找到

string="unix-bash 2389"
character="-"
printf '%s' "$string" | awk -vc="$character" '{ if (gsub(c, "")) { print "Found" } else { print "Not Found" } }'

输出:

建立

原始来源:http://unstableme.blogspot.com/2008/06/bash-search-letter-in-string-awk.html

其他回答

如果您喜欢正则表达式方法:

string='My string';

if [[ $string =~ "My" ]]; then
   echo "It's there!"
fi

此堆栈溢出答案是唯一一个陷阱空格和破折号字符的答案:

# For null cmd arguments checking   
to_check=' -t'
space_n_dash_chars=' -'
[[ $to_check == *"$space_n_dash_chars"* ]] && echo found

我使用这个函数(一个不包括但很明显的依赖项)。它通过了以下测试。如果函数返回值>0,则找到字符串。你也可以很容易地返回1或0。

function str_instr {
   # Return position of ```str``` within ```string```.
   # >>> str_instr "str" "string"
   # str: String to search for.
   # string: String to search.
   typeset str string x
   # Behavior here is not the same in bash vs ksh unless we escape special characters.
   str="$(str_escape_special_characters "${1}")"
   string="${2}"
   x="${string%%$str*}"
   if [[ "${x}" != "${string}" ]]; then
      echo "${#x} + 1" | bc -l
   else
      echo 0
   fi
}

function test_str_instr {
   str_instr "(" "'foo@host (dev,web)'" | assert_eq 11
   str_instr ")" "'foo@host (dev,web)'" | assert_eq 19
   str_instr "[" "'foo@host [dev,web]'" | assert_eq 11
   str_instr "]" "'foo@host [dev,web]'" | assert_eq 19
   str_instr "a" "abc" | assert_eq 1
   str_instr "z" "abc" | assert_eq 0
   str_instr "Eggs" "Green Eggs And Ham" | assert_eq 7
   str_instr "a" "" | assert_eq 0
   str_instr "" "" | assert_eq 0
   str_instr " " "Green Eggs" | assert_eq 6
   str_instr " " " Green "  | assert_eq 1
}

公认的答案是最好的,但由于有不止一种方法可以做到这一点,这里有另一种解决方案:

if [ "$string" != "${string/foo/}" ]; then
    echo "It's there!"
fi

${var/search/replace}是$var,如果找到了第一个搜索实例,则将其替换为replace(它不会更改$var)。如果您试图将foo替换为空,并且字符串发生了更改,那么很明显找到了foo。

Bash 4+示例。注意:当单词包含空格等时,不使用引号会导致问题。请始终在Bash、IMO中引用。

以下是一些Bash 4+示例:

示例1,检查字符串中的“yes”(不区分大小写):

    if [[ "${str,,}" == *"yes"* ]] ;then

示例2,检查字符串中的“yes”(不区分大小写):

    if [[ "$(echo "$str" | tr '[:upper:]' '[:lower:]')" == *"yes"* ]] ;then

示例3,检查字符串中的“yes”(区分大小写):

     if [[ "${str}" == *"yes"* ]] ;then

示例4,检查字符串中的“yes”(区分大小写):

     if [[ "${str}" =~ "yes" ]] ;then

示例5,完全匹配(区分大小写):

     if [[ "${str}" == "yes" ]] ;then

示例6,完全匹配(不区分大小写):

     if [[ "${str,,}" == "yes" ]] ;then

示例7,完全匹配:

     if [ "$a" = "$b" ] ;then

示例8,通配符match.ext(不区分大小写):

     if echo "$a" | egrep -iq "\.(mp[3-4]|txt|css|jpg|png)" ; then

示例9,对区分大小写的字符串使用grep:

     if echo "SomeString" | grep -q "String"; then

示例10,对不区分大小写的字符串使用grep:

     if echo "SomeString" | grep -iq "string"; then

示例11,对字符串使用grep,不区分大小写,带通配符:

     if echo "SomeString" | grep -iq "Some.*ing"; then

示例12,使用doublehash进行比较(如果变量为空会导致假阳性等)(区分大小写):

     if [[ ! ${str##*$substr*} ]] ;then  #found

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