bash shell：在同一行中grepping两个字符串并在if-condition中使用它

Question

grep string1 file1.txt | grep -q string2
if [ $? == 0 ]; then
    echo "both string1 and 2 found"
else
    echo "either or both missing"
fi

I need to find both string1 and string 2 in same line from file1.txt, is there any better way to write this or this is the good already? thanks for all the help, I am new to shell programming.

Answer 1

you can use

grep -e "string1.*string2" file1.txt

so long as you're expecting string2 to come second and there is no overlap

Alternatively the grep piped into grep is the standard approach. Maybe using a variable

result=`grep string1 file1.txt | grep string2`
if [ `echo "$result"|wc -w` == 0 ];then
  echo "a"
else
  echo "b"
fi

Answer 2

如果订单无关紧要，它已经相当不错了，但您可以将其缩短为：

grep string1 file1.txt | grep -q string2 && echo found || echo not found

Answer 3

Usually, you only need to use $? if you need to compare it against several different values. In this case, you only care about 0-vs-non-zero, so just run the grep commands in the if statement itself.

if grep string1 file1.txt | grep -q string2; then
    echo "both string1 and 2 found"
else
    echo "either or both missing"
fi