linux判断目录，文件存在等

1. shell判断文件,目录是否存在或者具有权限
2. #!/bin/sh
4. myPath="/var/log/httpd/"
5. myFile="/var /log/httpd/access.log"

7. 这里的-x 参数判断$myPath是否存在并且是否具有可执行权限

8. if [ ! -x “$myPath”]; then

9. error 少一个空格识别不了

10. if [ ! -x “$myPath” ]; then
11. mkdir “$myPath”
12. fi

14. 这里的-d 参数判断$myPath是否存在

15. if [ ! -d “$myPath”]; then
16. mkdir “$myPath”
17. fi

19. 这里的-f参数判断$myFile是否存在

20. if [ ! -f “$myFile” ]; then
21. touch “$myFile”
22. fi

24. 其他参数还有-n,-n是判断一个变量是否是否有值

25. if [ ! -n “$myVar” ]; then
26. echo “$myVar is empty”
27. exit 0
28. fi

30. 两个变量判断是否相等

31. if [ “$var1"="$var2” ]; then
32. echo ‘$var1 eq $var2’
33. else
34. echo ‘$var1 not eq $var2’
35. fi

-f 和-e的区别
Conditional Logic on Files

-a file exists.
-b file exists and is a block special file.
-c file exists and is a character special file.
-d file exists and is a directory.
-e file exists (just the same as -a).
-f file exists and is a regular file.
-g file exists and has its setgid(2) bit set.
-G file exists and has the same group ID as this process.
-k file exists and has its sticky bit set.
-L file exists and is a symbolic link.
-n string length is not zero.
-o Named option is set on.
-O file exists and is owned by the user ID of this process.
-p file exists and is a first in, first out (FIFO) special file or
named pipe.
-r file exists and is readable by the current process.
-s file exists and has a size greater than zero.
-S file exists and is a socket.
-t file descriptor number fildes is open and associated with a
terminal device.
-u file exists and has its setuid(2) bit set.
-w file exists and is writable by the current process.
-x file exists and is executable by the current process.
-z string length is zero.

my log

download.sh

#!/usr/bin/bash
cat  manifest.txt | while read row
do
path=`dirname $row`
# para -d check dir
if [ ! -d "$path"]; then
# error 少一个空格
if [ ! -d "$path" ]; then
mkdir -p "$path"
fi
# para -f check file
if [ ! -f "$row" ]; then
cd  "$path"
wget https://ftp.ncbi.nlm.nih.gov/genomes/${row}
cd -
fi
done