Bash中存在测试文件

Question

I want to test existence of a file using a Bash script of but get "no file exists..." message even if the file ACTUALLY exists:

#!/bin/bash
# Usage : myscript.sh AAAAMMJJ
# where AAAAMMJJ is the argument passed to the script  

d_date=$1

# No accurate content here...
# $d_date value is 20160708
# $d_year value is 2016
# $d_month value is 07
# $d_day value is 08

# Directory path
p_path="/home/user/mydir/${year}"

# Filename is something like: my-file_20160708z.html
f_file="${$p_path}/my-file_${d_date}z.html"

# Testing if file exists
[ ! -f "${f_file}" ] && echo "File OK" || echo "no file..."

What is the proper way to test file existence with this kind of construct? This works perfectly with another file (".txt" file).

Answer 1

You wrote:

# Testing if file exists
[ ! -f "${f_file}" ] && echo "File OK" || echo "no file..."

What you should have written:

# Testing if file exists
[ -f "${f_file}" ] && echo "File OK" || echo "no file..."

Explanation

man test :

( EXPRESSION )

EXPRESSION is true

! EXPRESSION

EXPRESSION is false

So when you write just an expression, success means true.

-f FILE

FILE exists and is a regular file

So, if you wanted to test a file exists, you wouldn't negate the -f test by putting a ! , that would do the opposite.