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Sometimes, we have met issue how to check whether one file exists using shell script.
you use "-e" or "-f" ? the two of them have some different which may mislead you if you don't know their exact usage.
| -f filename | Return true filename exists and is a regular file, not including link file, directory, block special, character special |
| -e filename | Return true filename exists (regardless of type). |
"regular file", as most UNIX/POSIX docs refer generically to all types of file system entries a simply "files", e.g., a symbolic link is a type of a file, as is a named pipe, regular file, directory, block special, character special, socket, et(转https://www.cyberciti.biz/tips/find-out-if-file-exists-with-conditional-expressions.html)
So, you see -e might stop you making mistakes.
Append the full list to check file exist.
| [ Expression ] | Meaning |
|---|---|
| -b filename | Return true if filename is a block special file. |
| -c filename | Return true if filename exists and is a character special file. |
| -d filename | Return true filename exists and is a directory. |
| -e filename | Return true filename exists (regardless of type). |
| -f filename | Return true filename exists and is a regular file. |
| -g filename | Return true filename exists and its set group ID flag is set. |
| -h filename | Return true filename exists and is a symbolic link. This operator is retained for compatibility with previous versions of this program. Do not rely on its existence; use -L instead. |
| -k filename | Return true filename exists and its sticky bit is set. |
| -n filename | Return true the length of string is nonzero. |
| -p filename | Return true filename is a named pipe (FIFO). |
| -r filename | Return truefilename exists and is readable. |
| -s filename | Return true filename exists and has a size greater than zero. |
| -t file_descriptor | Return true the filename whose file descriptor number is file_descriptor is open and is associated with a terminal. |
| -u filename | Return true filename exists and its set user ID flag is set. |
| -w filename | Return true filename exists and is writable. True indicates only that the write flag is on. The file is not writable on a read-only file system even if this test indicates true. |
| -x filename | Return true filename exists and is executable. True indicates only that the execute flag is on. If file is a directory, true indicates that file can be searched. |
| -z string | Return true the length of string is zero. |
| -L filename | Return true filename exists and is a symbolic link. |
| -O filename | Return true filename exists and its owner matches the effective user id of this process. |
| -G filename | Return true filename exists and its group matches the effective group id of this process. |
| -S filename | Return true filename exists and is a socket. |
| file1 -nt file2 | True if file1 exists and is newer than file2. |
| file1 -ot file2 | True if file1 exists and is older than file2. |
| file1 -ef file2 | True if file1 and file2 exist and refer to the same file. |