### Install QDirStat

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

Install QDirStat after compiling. This command typically installs to the default /usr directory. Use 'su -c make install' for root privileges if needed.

```bash
sudo make install
```

--------------------------------

### Build and Install Software Manually

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Unpkg-View.md

Standard command sequence for compiling and installing software directly to system directories.

```bash
make && sudo make install
```

--------------------------------

### Install and Run QDirStat from Live Media

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Shadowed-by-Mount.md

Install QDirStat on a live Linux system using `apt` and then run it with `sudo` to analyze a mounted filesystem. Running with `sudo` ensures access to all subdirectories.

```bash
tux@live-linux:~$ sudo apt install qdirstat
tux@live-linux:~$ xhost +
tux@live-linux:~$ sudo qdirstat /mnt
```

--------------------------------

### Install QDirStat Packages on Ubuntu

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

Use this command to install the necessary packages for building QDirStat on Ubuntu. It includes build essentials, Qt6 development files, and zlib.

```bash
sudo apt-get install build-essential qtbase6-dev qt6-5compat-dev zlib1g-dev
```

--------------------------------

### Install QDirStat to Custom Directory

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

Install QDirStat to a custom directory by specifying the INSTALL_PREFIX during the qmake6 configuration. This is useful for non-standard installations.

```bash
qmake6 INSTALL_PREFIX=/usr/local
```

--------------------------------

### Install QDirStat Packages on SUSE

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

Install the required development packages for building QDirStat on SUSE Linux. This includes C/C++ development tools, Qt6 development files, and zlib.

```bash
sudo zypper install -t pattern devel_C_C++
sudo zypper install qt6-widgets-devel qt6-qt5compat-devel zlib-devel
```

--------------------------------

### Start QDirStat with Package Filter (Starts With)

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Pkg-View.md

Launch QDirStat and filter packages starting with 'chrom'. This uses auto-mode, defaulting to a 'starts with' match for package names. Patterns are case-insensitive.

```bash
qdirstat pkg:/chrom
```

--------------------------------

### QDirStat Cache File Format Example

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/cache-file-format.txt

An example of a QDirStat cache file in version 2.0 format. This format is used for storing directory and file information. Lines starting with '#' are comments and are ignored.

```text
# Generated by qdirstat-cache-writer
# Do not edit!
#
# Type  path                            size     uid   gid  perm.       mtime      <optional fields>

D /work/home/sh/src/qdirstat            4096    1000  1000  0775        0x65e0ce47
```

--------------------------------

### Generate Dpkg File Lists

Source: https://github.com/shundhammer/qdirstat/blob/master/scripts/pkg-tools/README.md

Creates lists of installed packages and their files for dpkg-based systems. Output paths are printed to stdout. The QDirStat temporary directory is created if it doesn't exist.

```bash
[sh @ balrog] ...qdirstat/scripts/pkg-tools % complete-filelist-dpkg
2459 /tmp/qdirstat-sh/pkglist.txt
268507 /tmp/qdirstat-sh/filelist.txt
```

--------------------------------

### Install URI::Escape Perl Module

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/QDirStat-for-Servers.md

Install the URI::Escape Perl module using cpan. Ensure 'make' is installed if the installation fails.

```bash
cpan URI::Escape
```

--------------------------------

### Retrieve Installed Package List

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Pkg-View.md

Commands used by QDirStat to fetch the list of installed packages from the system.

```bash
dpkg-query --show --showformat='${Package} | ${Version} | ${Architecture} | ${Status}\n'
```

```bash
rpm -qa --queryformat '%{name} | %{version}-%{release} | %{arch}\n'
```

```bash
pacman -Qn
```

--------------------------------

### Start QDirStat with Unpackaged Files View

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Unpkg-View.md

Launches QDirStat directly into the unpackaged files view for a specified directory. Uses previously saved exclude and ignore patterns.

```bash
qdirstat unpkg:/usr/share
```

```bash
qdirstat unpkg:/
```

--------------------------------

### Select Qt6 Environment on Ubuntu

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

If you have multiple Qt versions installed, use qtchooser to select Qt6 for building QDirStat. This ensures the correct Qt libraries are used.

```bash
sudo apt-get install qtchooser
export QT_SELECT="qt6"
```

--------------------------------

### Display Disk Usage of Qt Installation Directory

Source: https://github.com/shundhammer/qdirstat/wiki/QDirStat-MacOS-Dev

Use 'du -skh *' to display disk usage for each item in the current directory. This is useful for understanding the space occupied by a Qt installation.

```bash
cd ~/qt
du -skh *

```

--------------------------------

### Start QDirStat with Package Filter (Wildcard)

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Pkg-View.md

Launch QDirStat and filter for packages containing 'gtk'. The '*' wildcards must be quoted to prevent shell expansion. Patterns are case-insensitive.

```bash
qdirstat "pkg:/*gtk*"
```

--------------------------------

### Start QDirStat with Package Filter (Regular Expression)

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Pkg-View.md

Launch QDirStat and filter for packages matching the regular expression '.*qt[45].*'. This selects packages related to Qt4 or Qt5. Patterns are case-insensitive.

```bash
qdirstat "pkg:/.*qt[45].*"
```

--------------------------------

### Profile QDirStat with Valgrind

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Debugging-Tips.md

Start QDirStat with Valgrind's callgrind tool to profile its execution. This significantly slows down the application, so avoid using very large directories. Results are saved to callgrind.out.* files.

```bash
valgrind --tool=callgrind --dump-instr=yes --simulate-cache=yes --collect-jumps=yes qdirstat ~
```

--------------------------------

### Filter Snap Packages with df

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/DevHistory.md

Example command to identify snap package loopback mounts cluttering filesystem output.

```bash
df -hT | grep snap

/dev/loop0  squashfs  159M  159M  0 100% /snap/chromium/1244
/dev/loop1  squashfs   55M   55M  0 100% /snap/core18/1880
/dev/loop2  squashfs   63M   63M  0 100% /snap/gtk-common-themes/1506
/dev/loop3  squashfs   30M   30M  0 100% /snap/snapd/8542
```

--------------------------------

### Start QDirStat with Package Filter (Multiple Regex)

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Pkg-View.md

Launch QDirStat and filter for packages matching a list of common browser names using a regular expression. Use anchors like '^' and '$' for precise matching if needed, as regex uses partial matching by default. Patterns are case-insensitive.

```bash
qdirstat "pkg:/(firefox|mozilla|chrome|chromium|opera)"
```

--------------------------------

### Start QDirStat with Package Filter (Exact Match)

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Pkg-View.md

Launch QDirStat and filter for the exact package name 'emacs'. The '=' prefix explicitly sets the match mode to 'exact match'. Patterns are case-insensitive.

```bash
qdirstat pkg:/=emacs
```

--------------------------------

### Display QDirStat Help

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

View all available command-line options for QDirStat by using the --help option.

```bash
qdirstat --help
```

--------------------------------

### Bind-Mount Multiple Directories

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Shadowed-by-Mount.md

Demonstrates creating target directories and performing bind-mounts for multiple distinct directories, ensuring unique target paths to avoid shadowing.

```bash
root@linux:~# mkdir -p /mnt/shadowed/win_app
root@linux:~# mount -o bind /mnt/root/win/app /mnt/shadowed/win_app
root@linux:~# mkdir -p /mnt/shadowed/win_boot
root@linux:~# mount -o bind /mnt/root/win/app /mnt/shadowed/win_boot
```

--------------------------------

### Build QDirStat on MacOS

Source: https://github.com/shundhammer/qdirstat/wiki/QDirStat-MacOS-Dev

Follow these steps to clone the QDirStat repository, configure the build with qmake, and compile the application using make. The resulting executable will be in a .app directory.

```bash
mkdir ~/work
cd ~/work
git clone https://github.com/shundhammer/qdirstat.git
cd qdirstat
qmake
make
```

--------------------------------

### Start QDirStat Without Directory Prompt

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Unpkg-View.md

Starts QDirStat without prompting for a directory, allowing immediate access to the menu for selecting a scan target.

```bash
qdirstat -d
```

--------------------------------

### Launch QDirStat via Command Line

Source: https://context7.com/shundhammer/qdirstat/llms.txt

Use these commands to launch the QDirStat application with specific directories, cache files, or specialized views.

```bash
# Basic usage - scan a directory
qdirstat /home/user/Documents

# Scan with slow update mode (3 sec intervals instead of 333 ms)
qdirstat --slow-update /home/user
qdirstat -s /var/log

# Start without showing the directory selection dialog
qdirstat --dont-ask
qdirstat -d

# Read from a pre-generated cache file
qdirstat --cache /path/to/cache.gz
qdirstat -c /tmp/server-cache.qdirstat.cache.gz

# View installed packages matching a pattern (starts with "chrom")
qdirstat pkg:/chrom

# View all Qt4 or Qt5 packages using regex
qdirstat "pkg:/.*qt[45].*"

# View exact package name only
qdirstat "pkg:/=emacs"

# View unpackaged files in system directories
qdirstat unpkg:/usr/share
qdirstat unpkg:/

# Show help
qdirstat --help
```

--------------------------------

### List All Block Devices with lsblk

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Shadowed-by-Mount.md

Use `lsblk` to display all block devices and their partitions, regardless of whether they are mounted. This command does not require root permissions.

```console
sh@balrog:~$ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 931,5G  0 disk
├─sda1   8:1    0  97,7G  0 part /win/boot
└─sda2   8:2    0 833,9G  0 part /win/app
sdb      8:16   0 931,5G  0 disk
├─sdb1   8:17   0     2G  0 part
├─sdb2   8:18   0    30G  0 part /hd-root-18-04
├─sdb3   8:19   0    30G  0 part /hd-root-14-04
├─sdb4   8:20   0     1K  0 part
└─sdb5   8:21   0 869,5G  0 part /work
sdc      8:32   0 232,9G  0 disk
├─sdc1   8:33   0     2G  0 part [SWAP]
├─sdc2   8:34   0    30G  0 part /
├─sdc3   8:35   0    30G  0 part /ssd-root-20-04
└─sdc4   8:36   0 170,9G  0 part /ssd-work
sr0     11:0    1  1024M  0 rom
```

--------------------------------

### Create New Feature Branch

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/GitHub-Workflow.md

Starts a new development branch based on the current state of the pull request branch.

```bash
git branch kilroy-hyperforble
git checkout kilroy-hyperforble
...(work in that branch...)
```

--------------------------------

### List Block Devices and Mount Filesystem

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Shadowed-by-Mount.md

Use `lsblk` to identify partitions and `mount` to access a specific partition from a live environment. This is useful for inspecting filesystems that might be inaccessible from the running system.

```bash
tux@live-linux:~$ lsblk /dev/sdb
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb      8:16   0 931,5G  0 disk
├─sdb1   8:17   0     2G  0 part
├─sdb2   8:18   0    30G  0 part
├─sdb3   8:19   0    30G  0 part
├─sdb4   8:20   0     1K  0 part
└─sdb5   8:21   0 869,5G  0 part
tux@live-linux:~$ sudo mount /dev/sdb2 /mnt
```

--------------------------------

### Rename Git Remote

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/GitHub-Workflow.md

Rename an existing Git remote, for example, changing 'origin' to 'mine'. This is useful if the default remote name was not set as desired during cloning.

```bash
git remote rename origin mine
```

--------------------------------

### Compile QDirStat

Source: https://github.com/shundhammer/qdirstat/blob/master/README.md

Compile QDirStat from source after setting up the build environment. Navigate to the source directory and run qmake6 followed by make.

```bash
qmake6
make
```

--------------------------------

### Download and Make Executable qdirstat-cache-writer

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/QDirStat-for-Servers.md

Download the qdirstat-cache-writer script to the server and make it executable. It's recommended to review the script's content for security.

```bash
ssh root@myserver
cd /usr/local/bin
wget https://github.com/shundhammer/qdirstat/raw/master/scripts/qdirstat-cache-writer
chmod 755 qdirstat-cache-writer
```

--------------------------------

### Open QDirStat Application on MacOS

Source: https://github.com/shundhammer/qdirstat/wiki/QDirStat-MacOS-Dev

After building QDirStat, you can open the application bundle using the 'open' command or by navigating to it in Finder.

```bash
cd qdirstat.app
open qdirstat.app
```

--------------------------------

### Clear Linux Disk Caches

Source: https://github.com/shundhammer/qdirstat/wiki/disk-usage-tools-compared

Use this command in a root shell to clear the kernel directory caches before performance testing. This ensures consistent results by starting with a cold cache.

```bash
echo 3 >/proc/sys/vm/drop_caches
```

--------------------------------

### Create and Checkout a Feature Branch

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/GitHub-Workflow.md

Start by checking out the master branch, then create and switch to a new feature branch for your work. This isolates your changes and makes managing pull requests easier.

```git
git checkout master
git branch kilroy-transmogrify
git checkout kilroy-transmogrify
```

--------------------------------

### Inspect shadowed files with QDirStat

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Shadowed-by-Mount.md

Launch QDirStat to visually inspect and manage shadowed files.

```console
root@linux:~# qdirstat /mnt/shadowed
```

--------------------------------

### C++ Brace Style Example

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/Contributing.md

Follow this brace style for C++ code, with opening braces on new lines and spaces after opening and before closing parentheses. Avoid K&R style.

```cpp
if ( someCondition )
{
    doSomething( arg1, arg2 )
}
```

--------------------------------

### Access Application Settings

Source: https://context7.com/shundhammer/qdirstat/llms.txt

Manage application configuration using QSettings and the Settings class. Use fixFileOwners to correct permissions after sudo operations.

```cpp
#include "Settings.h"
#include <QSettings>

// Access settings (uses QSettings internally)
QSettings settings;

// General settings
settings.beginGroup("MainWindow");
bool showTreemap = settings.value("ShowTreemap", true).toBool();
int treemapHeight = settings.value("TreemapHeight", 300).toInt();
settings.endGroup();

// Directory tree settings
settings.beginGroup("DirectoryTree");
bool crossFilesystems = settings.value("CrossFilesystems", false).toBool();
int slowUpdateMs = settings.value("SlowUpdateMillisec", 3000).toInt();
settings.endGroup();

// Treemap settings
settings.beginGroup("Treemap");
int minTileSize = settings.value("MinTileSize", 3).toInt();
bool squarified = settings.value("Squarify", true).toBool();
settings.endGroup();

// Package view settings
settings.beginGroup("Pkg");
int maxParallel = settings.value("MaxParallelProcesses", 6).toInt();
int minCacheSize = settings.value("MinCachePkgListSize", 200).toInt();
settings.endGroup();

// Cleanup settings are stored per-cleanup in numbered groups:
// [Cleanup_01], [Cleanup_02], etc.

// MIME categories stored in:
// [MimeCategory_01], [MimeCategory_02], etc.

// Exclude rules stored in:
// [ExcludeRule_01], [ExcludeRule_02], etc.

// Fix file ownership after running with sudo
QDirStat::Settings::fixFileOwners();
```

--------------------------------

### Collect Disk Usage Data on Server

Source: https://github.com/shundhammer/qdirstat/blob/master/doc/QDirStat-for-Servers.md

Use qdirstat-cache-writer with root permissions to collect disk usage data for specified filesystems. The first argument is the scan start point, and the last is the output cache file name.

```bash
sudo qdirstat-cache-writer /    myserver-root.cache.gz
sudo qdirstat-cache-writer /var myserver-var.cache.gz
sudo qdirstat-cache-writer /srv myserver-srv.cache.gz
```