Linux bash脚本-

Question

I am trying to use whether or not a line contains a date as a condition for an if statement:

if [grep -n -v '[0-9][0-9][0-9][0-9]' $line |wc -l==0]
then
...

The above returns an error. I don't necessarily need to use grep. The line processed by grep would look like:

1984 Dan Marino QB Miami Dolphins 

Any help is appreciated.

Answer 1

if [[ $(echo $line | grep -q '[0-9][0-9][0-9][0-9]') ]]; then

# do something
fi

Answer 2

You can check this using bash built-ins:

re='\b[[:digit:]]{4}\b'
if [[ $line =~ $re ]] ; then 
  echo ok; 
fi

Answer 3

[grep -n -v '[0-9][0-9][0-9][0-9]' $line |wc -l==0]

problem 1: [(space).....(space)] you need those spaces

problem 2: there is no [ foo==bar ] you can do something like [ $(echo "0") = "0" ] or [[ $(echo "0") == 0 ]] here the $(echo "0") is an example, you should fill with your commands.

Answer 4

You can just call grep with -q option and check the return value:

if [ $(grep -qv '[0-9][0-9][0-9][0-9]' $line) -eq 0 ]; then
   # ...
fi

Answer 5

使用命令替换和正确的bash语法。

 [[ "`grep -n -v '[0-9][0-9][0-9][0-9]' $line | wc -l`" -eq 0 ]]