How to use the command fzf (with examples)

fzf is a command-line fuzzy finder that allows users to quickly search and select items from a list. It is similar to the “sk” command and can be used to search and filter through various types of data, such as files, running processes, and more.

Use case 1: Start fzf on all files in the specified directory

Code:

find path/to/directory -type f | fzf

Motivation: This use case is helpful when you want to search and select a specific file from a large directory. Instead of manually navigating through the directory structure, fzf allows you to quickly search and filter files using fuzzy matching.

Explanation:

• find path/to/directory -type f - This command lists all files in the specified directory. The find command is used to traverse a directory recursively and the -type f option specifies that only regular files should be included.
• | - The pipe symbol used in shell commands allows the output of the previous command to be used as input for the next command.
• fzf - This command starts the fzf fuzzy finder on the list of files generated by the previous command.

Example output:

/path/to/directory/file1.txt
/path/to/directory/file2.txt
/path/to/directory/file3.txt

Use case 2: Start fzf for running processes

Code:

ps aux | fzf

Motivation: When working with multiple processes running on the system, it can be difficult to locate a specific process to perform actions such as killing or inspecting its details. Using fzf with the ps aux command helps to quickly search and select a process based on its name or other attributes.

Explanation:

• ps aux - This command lists all running processes along with detailed information. The aux options are used to display all processes for all users in a user-friendly format.
• | - The pipe symbol used in shell commands allows the output of the previous command to be used as input for the next command.
• fzf - This command starts the fzf fuzzy finder on the list of running processes generated by the previous command.

Example output:

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.2 225672 26848 ?        Ss   Jul21   0:04 /sbin/init
root         2  0.0  0.0      0     0 ?        S    Jul21   0:00 [kthreadd]
...

Use case 3: Select multiple files with Shift + Tab and write to a file

Code:

find path/to/directory -type f | fzf --multi > path/to/file

Motivation: This use case is useful when you need to select multiple files from a list and save the selections to a file. It allows you to efficiently perform batch operations on selected files or create a custom list for further processing.

Explanation:

• find path/to/directory -type f - This command lists all files in the specified directory, as in the first use case.
• | - The pipe symbol used in shell commands allows the output of the previous command to be used as input for the next command.
• fzf --multi - The --multi option enables multiple selection mode in fzf, allowing you to select multiple files using Shift + Tab.
• > - This symbol is used for output redirection, where the output of the previous command is saved to a file.
• path/to/file - This is the path to the file where the selected files will be saved.

Example output: Selected files: file1.txt, file2.txt

Use case 4: Start fzf with a specified query

Code:

fzf --query "query"

Motivation: When you know the specific item you want to search for in a large list, using fzf with a specified query simplifies the searching process. It immediately displays the matched item and allows you to proceed with further actions.

Explanation:

• --query "query" - The --query option followed by a string allows you to pre-fill the fzf search input with the specified query string.
• query - This is the string you want to search for in the list.

Example output: If the query is “apple” and the list contains “apple”, “banana”, and “orange”, the result will be:

apple

Use case 5: Start fzf on entries that start with core and end with either go, rb, or py

Code:

fzf --query "^core go$ | rb$ | py$"

Motivation: This use case is beneficial when you want to filter a list based on specific patterns. In this example, it filters out entries that start with “core” and end with either “go”, “rb”, or “py”.

Explanation:

• --query "^core go$ | rb$ | py$" - The --query option followed by a regular expression allows you to filter the list based on the specified pattern.
• ^core go$ - This pattern filters entries that start with “core” and end with “go”.
• rb$ - This pattern filters entries that end with “rb”.
• py$ - This pattern filters entries that end with “py”.

Example output: If the list contains “corego”, “ruby”, “corepy”, and “python”, the matching entries will be:

corego
corepy

Use case 6: Start fzf on entries that do not match pyc and match exactly travis

Code:

fzf --query "!pyc 'travis"

Motivation: This use case is helpful when you want to exclude specific entries and match exactly another entry in a list. It allows you to filter the list based on negation and exact matching.

Explanation:

• --query "!pyc 'travis" - The --query option followed by a regular expression allows you to filter the list based on the specified pattern.
• !pyc - This pattern excludes entries that match “pyc”.
• 'travis - This pattern matches entries exactly equal to “travis”.

Example output: If the list contains “pycfile”, “trav”, “travis”, and “awesome”, the matching entry will be:

travis