Bash 循环控制 while if else 带返回
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Bash loop control while if else with a return
提问by MAXGEN
I need to return a true or false if I find a value within a file. I parse the file and if the value is located once which is enough, I want to break and return a true else return false. On top of it I need to pass the file into this check function. I'm trying to only use bash.
如果我在文件中找到一个值，我需要返回 true 或 false。我解析文件，如果该值定位一次就足够了，我想中断并返回真否则返回假。最重要的是，我需要将文件传递给这个检查函数。我试图只使用 bash。
is_file_contains_VAR(){
VARFILENAME=
while read LINE
do
if echo "$LINE" | grep -q "$VAR"; then
break
return 0
else
return 1
fi
done < $VARFILENAME
}
回答by ruakh
grep -qalready does what you want: it will abort as soon as it finds the string in question. So you can just write:
grep -q已经做了你想要的：它会在找到有问题的字符串后立即中止。所以你可以写：
function is_file_contains_VAR () {
grep -q -e "$VAR" ""
}
(Note: the -eis in case "$VAR"starts with a hyphen.)
（注意：-e以防万一"$VAR"以连字符开头。）
But for educational purposes . . . to write this as a loop, what you would want is to return 0as soon as there's a match, and only return 1at the very end, if you never find a match:
但出于教育目的。. . 要将其编写为循环，您想要的是return 0一旦有匹配项，并且仅return 1在最后，如果您从未找到匹配项：
function is_file_contains_VAR () {
local VARFILENAME=""
local LINE
while IFS= read -r LINE ; do
if grep -q -e "$VAR" <<< "$LINE" ; then
return 0
fi
done < "$VARFILENAME"
return 1
}
