# Check if File / Directory Exists In Bash, you can use the test command to check whether a file exists and determine the type of the file. The test command takes one of the following syntax forms: ``` test EXPRESSION [ EXPRESSION ] [[ EXPRESSION ]] ``` If you want your script to be portable, you should prefer using the old test `[` command, which is available on all POSIX shells. The new upgraded version of the test command `[[` (double brackets) is supported on most modern systems using Bash, Zsh, and Ksh as a default shell. ## Check if File Exists When checking if a file exists, the most commonly used FILE operators are `-e` and `-f`. The first one will check whether a file exists regardless of the type, while the second one will return true only if the FILE is a regular file (not a directory or a device). The most readable option when checking whether a file exists or not is to use the `test` command in combination with the [`if` statement](https://linuxize.com/post/bash-if-else-statement/) . Any of the snippets below will check whether the `/etc/resolv.conf` file exists: ``` FILE=/etc/resolv.conf if test -f "$FILE"; then echo "$FILE exists." fi ``` ``` FILE=/etc/resolv.conf if [ -f "$FILE" ]; then echo "$FILE exists." fi ``` ``` FILE=/etc/resolv.conf if [[ -f "$FILE" ]]; then echo "$FILE exists." fi ``` If you want to perform a different action based on whether the file exists or not simply use the if/then construct: ``` FILE=/etc/resolv.conf if [ -f "$FILE" ]; then echo "$FILE exists." else echo "$FILE does not exist." fi ``` Always use [double quotes](https://linuxize.com/post/echo-command-in-linux-with-examples/) to avoid issues when dealing with files containing whitespace in their names. You can also use the test command without the if statement. The command after the `&&` operator will only be executed if the [exit status](https://linuxize.com/post/bash-exit/) of the test command is true, ``` test -f /etc/resolv.conf && echo "$FILE exists." ``` ``` [ -f /etc/resolv.conf ] && echo "$FILE exists." ``` ``` [[ -f /etc/resolv.conf ]] && echo "$FILE exists." ``` If you want to run a series of command after the `&&` operator simply enclose the commands in curly brackets separated by `;` or `&&`: ``` [ -f /etc/resolv.conf ] && { echo "$FILE exist."; cp "$FILE" /tmp/; } ``` Opposite to `&&`, the statement after the `||` operator will only be executed if the exit status of the test command is `false`. ``` [ -f /etc/resolv.conf ] && echo "$FILE exist." || echo "$FILE does not exist." ``` ## Check if Directory Exist The operators `-d` allows you to test whether a file is a directory or not. For example to check whether the `/etc/docker` directory exist you would use: ``` FILE=/etc/docker if [ -d "$FILE" ]; then echo "$FILE is a directory." fi ``` ``` [ -d /etc/docker ] && echo "$FILE is a directory." ``` You can also use the double brackets `[[` instead of a single one `[`. ## Check if File does Not Exist Similar to many other languages, the test expression can be negated using the `!` (exclamation mark) logical not operator: ``` FILE=/etc/docker if [ ! -f "$FILE" ]; then echo "$FILE does not exist." fi ``` Same as above: ``` [ ! -f /etc/docker ] && echo "$FILE does not exist." ``` ## Check if Multiple Files Exist Instead of using complicated nested if/else constructs you can use `-a` (or `&&` with `[[`) to test if multiple files exist: ``` if [ -f /etc/resolv.conf -a -f /etc/hosts ]; then echo "Both files exist." fi ``` ``` if [[ -f /etc/resolv.conf && -f /etc/hosts ]]; then echo "Both files exist." fi ``` #### Equivalent variants without using the IF statement: ``` [ -f /etc/resolv.conf -a -f /etc/hosts ] && echo "Both files exist." ``` ``` [[ -f /etc/resolv.conf && -f /etc/hosts ]] && echo "Both files exist." ``` ## File test operators The test command includes the following FILE operators that allow you to test for particular types of files: * `-b` `FILE` - True if the FILE exists and is a special block file. * `-c` `FILE` - True if the FILE exists and is a special character file. * `-d` `FILE` - True if the FILE exists and is a directory. * `-e` `FILE` - True if the FILE exists and is a file, regardless of type (node, directory, socket, etc.). * `-f` `FILE` - True if the FILE exists and is a regular file (not a directory or device). * `-G` `FILE` - True if the FILE exists and has the same group as the user running the command. * `-h` `FILE` - True if the FILE exists and is a symbolic link. * `-g` `FILE` - True if the FILE exists and has set-group-id (`sgid`) flag set. * `-k` `FILE` - True if the FILE exists and has a sticky bit flag set. * `-L` `FILE` - True if the FILE exists and is a symbolic link. * `-O` `FILE` - True if the FILE exists and is owned by the user running the command. * `-p` `FILE` - True if the FILE exists and is a pipe. * `-r` `FILE` - True if the FILE exists and is readable. * `-S` `FILE` - True if the FILE exists and is a socket. * `-s` `FILE` - True if the FILE exists and has nonzero size. * `-u` `FILE` - True if the FILE exists, and set-user-id (`suid`) flag is set. * `-w` `FILE` - True if the FILE exists and is writable. * `-x` `FILE` - True if the FILE exists and is executable. ## Resources {% embed url="" %}