Bash脚本 - 检查文件是否包含特定行

Question

我需要检查文件是否包含特定行.这个文件是由某人连续写的,所以我把检查放在while循环中.

FILE="/Users/test/my.out"
STRING="MYNAME"
EXIT=1
while [ $EXIT -ne 0 ]; do 
    if [ -f $FILE ] ; then CHECK IF THE "STRING" IS IN THE FILE - IF YES echo "FOUND"; EXIT=0; fi
done

该文件包含文本和多行.

Answer 1

如果$FILE包含文件名并$STRING包含要搜索的字符串,则可以使用以下命令显示文件是否匹配:

if [ ! -z $(grep "$STRING" "$FILE") ]; then echo "FOUND"; fi

Answer 2

来自 grep 的人：

-q, --quiet, --silent
    Quiet; do not write anything to standard output.  Exit immediately with zero status if any match is found, even if an error was detected.  Also see the -s or --no-messages option.
-F, --fixed-strings
    Interpret PATTERNS as fixed strings, not regular expressions.
-x, --line-regexp
    Select only those matches that exactly match the whole line.  For a regular expression pattern, this is like parenthesizing the pattern and then surrounding it with ^ and $.

-q, --quiet, --silent
    Quiet; do not write anything to standard output.  Exit immediately with zero status if any match is found, even if an error was detected.  Also see the -s or --no-messages option.
-F, --fixed-strings
    Interpret PATTERNS as fixed strings, not regular expressions.
-x, --line-regexp
    Select only those matches that exactly match the whole line.  For a regular expression pattern, this is like parenthesizing the pattern and then surrounding it with ^ and $.

如果您需要检查整行，请使用-x标志：

# Inline
grep -q -F "$STRING" "$FILE" && echo 'Found' || echo 'Not Found'
grep -q -F "$STRING" "$FILE" || echo 'Not Found'

# Multiline
if grep -q -F "$STRING" "$FILE"; then
  echo 'Found'
else
  echo 'Not Found'
fi

if ! grep -q -F "$STRING" "$FILE"; then
  echo 'Not Found'
fi

Answer 3

轮询文件的修改时间,并在字符串发生变化时grep:

while :; do
    a=$(stat -c%Y "$FILE") # GNU stat
    [ "$b" != "$a" ] && b="$a" && \
        grep -q "$STRING" "$FILE" && echo FOUND
    sleep 1
done

注意:BSD用户应该使用 stat -f%m