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搜索关键字：

• linux shell string contain

参考链接：

• http://stackoverflow.com/questions/229551/string-contains-in-bash
• http://stackoverflow.com/questions/4277665/how-do-i-compare-two-string-variables-in-an-if-statement-in-bash
• http://stackoverflow.com/questions/2829613/how-do-you-tell-if-a-string-contains-another-string-in-unix-shell-scripting
• http://codingstandards.iteye.com/blog/1181490
• http://www.cnblogs.com/chengmo/archive/2010/10/02/1841355.html

参考解答：

1.通配符

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

2.正则匹配

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

3.switch…case版本的通配符(速度最快……)

string='My long string'
case "$string" in
  *foo*)
    # Do stuff
    ;;
esac

4.用grep来实现

string='My long string'
if grep -q foo <<<$string; then
    echo "It's there"
fi

5.用字符串替换/删除来实现

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

性能比较：

http://stackoverflow.com/a/25535717

#!/bin/bash
# Author:	ixyzero.com
# Date:		2015-11-7
# set -x
# export PS4='+${BASH_SOURCE}:${LINENO}:${FUNCNAME[0]}: '

#echo "$@"
#echo "$*"
#LOGGER="N"
#options="$@"
#if [ "$options" != "${options/--log/}" ]; then
#    LOGGER="Y"
#fi

function stringContain() { [ -z "${2##*$1*}" ]; }

# [[ $b =~ $a ]]
# [ "${b/$a//}" = "$b" ]
# [[ $b == *$a* ]]
# case $b in *$a) : ;; esac
# stringContain $a $b

/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do [[ $b =~ $a ]] ; x=$(($x-1)); done'
sleep 2
/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do [ "${b/$a//}" = "$b" ] ; x=$(($x-1)); done'
sleep 2
/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do [[ $b == *$a* ]] ; x=$(($x-1)); done'
sleep 2
/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do case $b in *$a) : ;; esac ; x=$(($x-1)); done'
sleep 2
/usr/bin/time bash -c 'function stringContain() { [ -z "${2##*$1*}" ]; }; a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do stringContain $a $b ; x=$(($x-1)); done'
sleep 2
/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do [ -z "${b##*$a*}" ] ; x=$(($x-1)); done'
sleep 2
/usr/bin/time bash -c 'a=two;b=onetwothree; x=100000; while [ $x -gt 0 ]; do [ "$b" != "${b/$a/}" ] ; x=$(($x-1)); done'

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