在shell脚本中使用if的多个条件

Question

I want to check if a file exists or not along with the no of lines = 4 in a single if condition . Can anyone help here.

if [[ -f report]] && [[`wc -l report` -eq 4 ]]; then
    echo " Proceed further"
else
    exit 1
fi

Answer 1

This is simpler:

{ [ `wc -l < report` -eq 4 ] || exit; } 2>/dev/null 
echo " Proceed further"

Notes:

• If report exists and is 4 lines long, then wc -l report returns:

   4 report 

  ...which -eq can't understand. Instead do wc -l < report which outputs an -eq -friendly:

   4 

• There's no need to check if report exists, since the < redirection will do that anyway, and returns the same error code.

• More specific exit codes. If report does not exist, the exit code is 2 . If report is 5 lines long, the exit code is 1 .