File System

View and navigate the contents of the files and directories on the file system.

Create and extract archives of files and directories.

Use $HOME and ~ within directory paths as convenient Short-cuts.

Use sudo with these commands to access files & directories with elevated permissions

List files and directories

ls command lists the contents of the current directory or the specified path.

ls -l shows the meta data of files, e.g. ownership, permissions, etc.

ls -a includes hidden dot-files in the list, e.g. .git

tree shows a recursive list of files and directories, e.g. show the whole contents of a code project.

pwd shows the full path of the current working directory

Disk usage

df -h shows all disk usage in the operating system, in human readable format

du -sh shows summary file use of the current directory (or specified path), including usage for sub-folders

Navigate the file system

cd to change to a different directory by giving the relative or full path

cd projects/practicalli

Short-cuts:

• cd move to the current user’s home directory
• cd .. move up a directory and can be used with a relative path cd ../sibling-directory
• cd – move to the previous directory

Change files and directories

touch filename creates a new file using the given name (assuming the file doesn't already exist)

mkdir path/to/target_folder/new-folder-name creates a new directory using a relative or full path, the current user has read, write, and execute files permissions in the new directory (-m flag or chmod to alter permissions)

mkdir -p path/that/doesnt/exist/yet the -p option will create all the directories that are not already present in the given path.

cp copies files using the form cp file1 file2 [target_path]. Use the -R flag to recursively copy a directory and its contents (including sub-directories)

mv moves (optionally rename) a file or directory to another location using the form mv file_or_directory [target_directory]

rm command deletes files from a directory. Uses the form: rm [options] file1 file2

Common flags for file and directory commands

-r (recursive) acts on a directory and its contents, including subdirectories.

-i (interactive) flag prompts for confirmation before running the command

-f (force) to run the command without confirmation

Shell may be configured to ask for delete confirmation

Archives

Tar (tape archive) is the long standing command for creating archives on Unix, optionally compressing the resulting file with one of several algorithms.

tar -cf tar_file_name.tar <directory and/or files> creates a new archive, -c for create, -f to specify archive file name.

tar -cfz archive.tgz <directory and/or files> creates a new archive using gzip compression.

Archive options:

• z gizip compression, .tgz file extension
• j bzip2 compression, .tgj file extension
• J xz compression, .tgx file extension

tar -xf archive.tar extracts everything from the archive, -C extracts to a given path.

tar can change the contents of an archive using --concatenate, --delete, --append and --update flags.

zip is a universal archive tool that compresses one or multiple files into a .zip archive, reducing the size of text based files. Binary files may result in a slightly bigger archive.

zip [options] zip_file_name <directory and/or files> creates a compressed archive.

unzip [options] zip_file_name extracts all the files form the archive.

Find files and contents

find to look for files and directories by a pattern

Append 2>/dev/null onto commands to silence permission errors

Find the exact file name anywhere on the file system (from the / root)

find / -name "secret-sauce.md" 2>/dev/null

-iname is case insensitive. Wild-cards * can also be used when the exact name is not known.

$ find / -iname "*secret*md" 2>/dev/null

find can execute a different command on results returned, e.g searching for files by content rather than name

$ find ~/Documents/ -name "*md" -exec grep -Hi squirrels {} \;
/home/practicalli/Documents/nature-in-action.md:I love watching squirrels play.

-maxdepth limits the number of directories to traverse

With hundreds of files in a default user directory and thousands more outside of that, sometimes you get more results from find than you want. You can limit the depth of searches with the -maxdepth option, followed by the number of directories you want find to descend into after the starting point:

$ find ~/secret-sauce.md -maxdepth 1

-mtime limits a search to files older or newer than a value times, by increments of 24 hours.

Find files in the current user account home directory, modified in the last 24 hours

find $HOME -mtime 0

Use a + before the value of -mtime as a conditional, matching files modified before 24 times the value.

Find log file which have not been update for more than a week.

find /var/log -iname "*~" -o -iname "*log*" -mtime +7

The - conditional find modified files within 24 hours times the value.

find /var/log -iname "*~" -o -iname "*log*" -mtime -7

-ls flag provides a long list showing meta data about the files found

$ find /var/log -iname "*~" -o -iname "*log*" -mtime -7 -ls
-rw-------  1 root root            0 Jun  9 18:20 /var/log/tallylog
-rw-------  1 root lp      332 Aug 11 15:05 /var/log/cups/error_log
-rw-------  1 root lp      332 Aug 11 15:05 /var/log/cups/access_log
-rw-------  1 root lp      332 Aug 11 15:05 /var/log/cups/page_log
-rw-------  1 root root  53733 Jun  9 18:24 /var/log/anaconda/anaconda.log
-rw-------  1 root root 835513 Jun  9 18:24 /var/log/anaconda/syslog
-rw-------  1 root root  21131 Jun  9 18:24 /var/log/anaconda/X.log

-ipath to search for a path within the file space

find / -type d -name 'img' -ipath "*public_html/practicalli*"