Idk

config/general/linux-examples.md

@@ -1,280 +0,0 @@
----
-title: Linux Examples
-breadcrumbs:
-- title: Configuration
-- title: General
----
-{% include header.md %}
-
-## Commands
-
-### General Monitoring
-
-- For more specific monitoring, see the other sections.
-- `htop`:
-    - ncurses-based process viewer like `top`, but prettier and more interactive.
-    - Install (APT): `apt install htop`
-    - Usage: `htop` (interactive)
-- `glances`:
-    - Homepage: [nicolargo.github.io/glances/](https://nicolargo.github.io/glances/)
-    - Install (PyPI for latest version): `pip3 install glances`
-    - ncurses-based viewer for e.g. basic system info, top-like process info, network traffic and disk traffic.
-    - Usage: `glances` (interactive)
-- `dstat`:
-    - A versatile replacement for vmstat, iostat and ifstat (according to itself).
-    - Prints scrolling output for showing a lot of types of general metrics, one line of columns for each time step.
-    - Usage: `dstat <options> [interval] [count]`
-        - Default interval is 1s, default count is unlimited.
-        - The values shown are the average since the last interval ended.
-        - For intervals over 1s, the last row will update itself each second until the delay has been reached and a new line is created. The values shown are averages since the last final value (when the last line was finalized), so e.g. a 10s interval gives a final line showing a 10s average.
-        - The first line is always a snapshot, i.e. all rate-based metrics are 0 or some absolute value.
-        - If any column options are provided, they will replace the default ones and are displayed in the order specified.
-    - Special options:
-        - `-C <>`: Comma-separated list of CPUs/cores to show for, including `total`.
-        - `-D <>`: Same but for disks.
-        - `-N <>`: Same but for NICs.
-        - `-f`: Show stats for all devices (not aggregated).
-    - Useful metrics:
-        - `-t`: Current time.
-        - `-p`: Process stats (by runnable, uninterruptible, new) (changes per second).
-        - `-y`: Total interrupt and context switching stats (by interrupts, context switches) (events per second).
-        - `-l`: Load average stats (1 min, 5 mins, 15 mins) (total system load multiplied by number of cores).
-        - `-c`: CPU stats (by system, user, idle, wait) (percentage of total).
-        - `--cpu-use`: Per-CPU usage (by CPU) (percentage).
-        - `-m`: Memory stats (by used, buffers, cache, free) (bytes).
-        - `-g`: Paging stats (by in, out) (count per second).
-        - `-s`: Swap stats (by used, free) (total).
-        - `-r`: Storage request stats (by read, write) (requests per second).
-        - `-d`: Storage throughput stats (by read, write) (bytes per second).
-        - `-n`: Network throughput stats (by recv, send) (bytes per second).
-        - `--socket`: Network socket stats (by total, tcp, udp, raw, ip-fragments)
-    - Useful plugins (metrics):
-        - `--net-packets`: Network request stats (by recv, send) (packets per second).
-    - Examples:
-        - General overview (CPU, RAM, ints/csws, disk, net): `dstat -tcmyrdn --net-packets 60`
-        - Network overview (CPU, ints/csws, net): `dstat -tcyn --net-packets 60`
-        - Process overview (CPU, RAM, ints/csws, paging, process, sockets): `dstat -tcmygp --socket 60`
-
-### File Systems and Logical Volume Managers
-
-- Partition disk: `gdisk <dev>` or `fdisk <dev>`
-- Create filesystem: `mkfs.<fs> <dev>`
-- Modify fstab:
-    - Test it with `mount -a` to make sure it doesn't have errors that may cause boot to fail.
-    - Run `systemctl daemon-reload` to avoid having systemd remount stuff that was removed from fstab or other weird shit.
-- Benchmark with IOzone:
-    - Install (Debian): `apt install iozone3`
-    - It uses the current dir.
-    - Test with various record sizes and file sizes: `iozone -a`
-    - Benchmark: `iozone -t1` (1 thread)
-    - Plot results: **TODO** It should be doable with gnuplot somehow.
-
-### Files
-
-- Search:
-    - By UID: `find / -user <UID>`
-    - Without a user: `find / -nouser`
-    - With setuid permission bit: `find / -perm /4000`
-    - Recursive search and replace: `find <dir> \( -type d -name .git -prune \) -o -type f -print0 | xargs -0 sed -i 's/123/456/g'`
-        - `-type d -name .git -prune` skips `.git` directories and can be excluded outside of git repos.
-- Usage:
-    - `du -sh <dirs>`
-    - K4DirStat (GUI) (package `k4dirstat`)
-- Shred files:
-    - `shred --remove --zero <file>`
-
-### Fun
-
-- Color text from STDIN: `lolcat`
-- `cowsay`
-- `fortune`
-
-### Hardware
-
-- Show hardware: `lshw`
-    - Run as root for more info.
-    - Specify `-X` to show GUI (requires `lshw-gtk`).
-- Show hardware topology: `lstopo` (requires hwloc)
-    - `lstopo` will try to present as a GUI. Use `lstopo-no-graphics` to force console output.
-- Show PCI devices: `lspci`
-- Show block devices: `lsblk`
-- Show USB devices: `lsusb`
-- Show CPUs: `lscpu`
-
-### Installations and Packages
-
-#### APT (Debian)
-
-- Find packages depending on the package: `apt rdepends --installed <package>`
-- Quickly add new repo: `add-apt-repository <repo-line`
-    - It will add the line to `/etc/apt/sources.list`, where you can manually remove it again.
-- Keys:
-    - List: `apt-key list`
-        - It will also show which file contains it.
-    - Remvoe key: `apt-key del <key-id>`
-        - The 8-digit hex key ID may either be found on `pub` line or as the last 8 hex digits on the continuation line.
-
-#### Pacman (Arch)
-
-- Full system upgrade: `pacman -Syu`
-- Search package: `pacman -Ss <package-name>`
-- Show package info: `pacman -Si <package>`
-- Install package: `pacman -S <packages>`
-    - Never use `-Sy` to avoid partial upgrades.
-- Remove package: `pacman -R <packages>`
-    - Remove orphans too: `-s`
-    - Purge configurations: `-n`
-
-### Network
-
-- Monitor usage:
-    - `nload <if>`
-    - `iftop -i <if>`
-    - `speedometer -t <if> -r <if> [...]`
-    - `dstat -tcyn --net-packets 60`
-- Monitor per-process usage:
-    - `nethog`
-- Test throughput:
-    - Internet: `speedtest` (from [speedtest.net](https://www.speedtest.net/apps/cli))
-    - Internal: `iperf3`
-- Show sockets (with `ss`):
-    - Example: `ss -tulpn`
-    - Note: `ss` replaces `netstat` and is mostly option compatible.
-    - Option `tu`: Include TCP and UDP sockets (no UNIX sockets).
-    - Option `l`: Include listening sockets (no client sockets).
-    - Option `p`: Show protocol (requires root).
-    - Option `n`: Don't translate port numbers to common service names.
-- Show misc. stats:
-    - Show kernel SNMP counters: `nstat`
-    - Show per-protocol stats: `netstat -s`
-- Bring interface up or down:
-    - Note: Your network manager probably has a more appropriate way to do this.
-    - Directly up or down interface: `ip link set dev <if> {up|down}`
-- Traffic shaping and link simulation:
-    - See `tc` to simulate e.g. random packet drop, random latencies, limited bandwidth etc.
-
-#### ip
-
-- General notes:
-    - Subcommands may be shortened (e.g. as `ip a` instead of `ip address`)
-    - For subcommands like `address` and `link`, it will default to show all elements if no further option is specified.
-- General options:
-    - Specified before the subcommand (e.g. `ip -c a`).
-    - `-c`: Show colored output.
-    - `-4` or `-6`: Show IPv4 or IPv6 addresses only.
-    - `-s`: Show stats (bytes, packets, errors, dropped, etc. for RX and TX).
-    - `-br`: Show brief with one line per interface (MAC address and status for `link`, addresses for `address`).
-    - `-o`: Show one line per interface (but all info unlike `-br`).
-    - `-j [-p]`: Print as JSON. Add `-p` for pretty printing.
-- Show L2/MAC addresses:
-    - Command: `ip link [show [<interface>]]`
-- Show L3/IP addresses:
-    - Command: `ip address [show [<interface> [scope <scope>]]]`
-    - Argument `scope global`: Only show global addresses (excludes localhost/`host`, link-local/`link`, etc.).
-- Show neighbors:
-    - Command: `ip neighbor`
-- Show routes:
-    - Command: `ip route`
-- Show multicast addresses:
-    - Command: `ip maddress`
-- Show multicast routes:
-    - Command: `ip mroute`
-
-#### tcpdump
-
-- Typical usage: `tcpdump -i <interface> -nn -v [filter]`
-- Options:
-    - `-w <>.pcap`: Write to capture file instead of formatted to STDOUT.
-    - `-i <if>`: Interface to listen on. Defaults to a random-ish interface.
-    - `-nn`: Don't resolve hostnames or ports.
-    - `-s<n>`: How much of the packets to capture. Use 0 for unlimited (full packet).
-    - `-v`/`-vv`: Details to show about packets. More V's for more details.
-    - `-l`: Line buffered more, for better stability when piping to e.g. grep.
-- Filters:
-    - Can consist of complex logical statements using parenthesis, `not`/`!`, `and`/`&&` and `or`/`||`. Make sure to quote the filter to avoid interference from the shell.
-    - Protocol: `ip`, `ip6`, `icmp`, `icmp6`, `tcp`, `udp`, ``
-    - Ports: `port <n>`
-    - IP address: `host <addr>`, `dst <addr>`, `src <addr>`
-    - IPv6 router solicitations and advertisements: `icmp6 and (ip6[40] = 133 or ip6[40] = 134)` (133 for RS and 134 for RA)
-    - IPv6 neighbor solicitations and advertisements: `icmp6 and (ip6[40] = 135 or ip6[40] = 136)` (135 for NS and 136 for NA)
-    - DHCPv4: `ip and udp and (port 67 and port 68)`
-    - DHCPv6: `ip6 and udp and (port 547 and port 546)`
-
-### Memory
-
-- NUMA stats:
-    - `numastat` (from package `numactl`)
-
-### Performance and Power Efficiency
-
-- Set the CPU frequency scaling governor mode:
-    - High performance: `echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor`
-    - Power save: `echo powersave | ...`
-- Show current core frequencies: `grep "cpu MHz" /proc/cpuinfo | cut -d' ' -f3`
-
-### Profiling
-
-- `time` (timing commands):
-    - Provided both as a shell built-in `time` and as `/usr/bin/time`, use the latter.
-    - Typical usage: `/usr/bin/time -p <command>`
-    - Options:
-        - `-p` for POSIX output (one line per time)
-        - `-v` for interesting system info about the process.
-    - It give the wall time, time spent in usermode and time spent in kernel mode.
-- `strace` (trace system calls and signals):
-    - In standard mode, it runs the full command and traces/prints all syscalls (including arguments and return value).
-    - Syntax: `strace [options] <command>`
-    - Useful options:
-        - `-c`: Show summary/overview only. (Hints at which syscalls are worth looking more into.)
-        - `-f`: Trace forked child processes too.
-        - `-e trace=<syscalls>`: Only trace the specified comma-separated list of syscalls.
-
-### Security
-
-- Show CPU vulnerabilities: `tail -n +1 /sys/devices/system/cpu/vulnerabilities/*`
-- Generate XKCD-style (multi-word) passwords (using package `xkcdpass`): `xkcdpass`
-
-### Storage
-
-- Test read speed: `hdparm -t <dev>` (safe)
-- Show IO load for devices: `iostat [-dxpm] [-t] [interval]`
-    - `-d`: Show only device usage.
-    - `-x` and `-p`: Include extended attributes and partitions.
-    - `-t` and interval: Show timestamp and repeat every x seconds.
-- Show IO usage for processes: `iotop -o [-a]`
-
-### System
-
-- Version info:
-    - Release info files:
-        - Debian (and Ubuntu): `/etc/debian_version`
-        - RHEL: `/etc/redhat-release`
-        - CentOS: `/etc/centos-release`
-    - General release info: `uname -a`
-    - Slightly more distro-specific release info: `lsb_release -a`
-- Monitor system load:
-    - `uptime`
-    - `iostat [-c] [-t] [interval]`
-- Monitor processes:
-    - `ps` (e.g. `ps aux` or `ps ax o uid,user:12,pid,comm`)
-- Monitor a mix of things: See the "general monitoring" section.
-- Monitor interrupts:
-    - `irqtop`
-    - `watch -n0.1 /proc/interrupts`
-- Run command with high or low CPU priority:
-    - Command: `nice -n<n> <cmd>` (`-20 <= n <= 19`)
-    - The nice value goes from -20 (highest priority) to 19 (lowest priority), with 0 as the default priority.
-    - The nice value is inherited by child processes (meaning forking processes maintains the nice value it started with).
-    - Use `renice` to change the value.
-    - Use `ionice` to set the I/O scheduler and scheduler-specific priority.
-- Stress test with stress-ng:
-    - Install (Debian): `apt install stress-ng`
-    - Stress CPU: `stress-ng -c $(nproc) -t $((10*60))` (use all CPU threads for 10 minutes)
-
-## Tasks
-
-### Burn Windows ISO (Ubuntu)
-
-1. Install the graphical application `woeusb` from `ppa:nilarimogard/webupd8`.
-
-{% include footer.md %}

config/general/linux-general.md

@@ -13,21 +13,321 @@ breadcrumbs:
 - [Linux Hardening Checklist](https://github.com/trimstray/linux-hardening-checklist)
 - [The Practical Linux Hardening Guide](https://github.com/trimstray/the-practical-linux-hardening-guide)
 
-## Distros
+## Information
 
-### Debian/Ubuntu
+### Distros
+
+#### Debian/Ubuntu
 
 - Nobody user and group: `nobody:nogroup`
 - List of default groups: (SystemGroups (Debian Wiki))[https://wiki.debian.org/SystemGroups#Other_System_Groups]
 - Release info file: `/etc/debian_version`
 
-### RHEL/CentOS
+#### RHEL/CentOS
 
 - Nobody user and group: `nobody:nobody`
 - Release info file: `/etc/redhat-release` or `/etc/centos-release`
 
-## Miscellaneous
+### Miscellanea
 
 - `urandom` VS `random`: `random` blocks when running out of entropy while `urandom` does not. For all practical purposes, `urandom` will almost never be *less random* than `random` and `random` may block at inappropriate times, so always use `urandom`.
 
+## Commands
+
+### General Monitoring
+
+- For more specific monitoring, see the other sections.
+- `htop`:
+    - ncurses-based process viewer like `top`, but prettier and more interactive.
+    - Install (APT): `apt install htop`
+    - Usage: `htop` (interactive)
+- `glances`:
+    - Homepage: [nicolargo.github.io/glances/](https://nicolargo.github.io/glances/)
+    - Install (PyPI for latest version): `pip3 install glances`
+    - ncurses-based viewer for e.g. basic system info, top-like process info, network traffic and disk traffic.
+    - Usage: `glances` (interactive)
+- `dstat`:
+    - A versatile replacement for vmstat, iostat and ifstat (according to itself).
+    - Prints scrolling output for showing a lot of types of general metrics, one line of columns for each time step.
+    - Usage: `dstat <options> [interval] [count]`
+        - Default interval is 1s, default count is unlimited.
+        - The values shown are the average since the last interval ended.
+        - For intervals over 1s, the last row will update itself each second until the delay has been reached and a new line is created. The values shown are averages since the last final value (when the last line was finalized), so e.g. a 10s interval gives a final line showing a 10s average.
+        - The first line is always a snapshot, i.e. all rate-based metrics are 0 or some absolute value.
+        - If any column options are provided, they will replace the default ones and are displayed in the order specified.
+    - Special options:
+        - `-C <>`: Comma-separated list of CPUs/cores to show for, including `total`.
+        - `-D <>`: Same but for disks.
+        - `-N <>`: Same but for NICs.
+        - `-f`: Show stats for all devices (not aggregated).
+    - Useful metrics:
+        - `-t`: Current time.
+        - `-p`: Process stats (by runnable, uninterruptible, new) (changes per second).
+        - `-y`: Total interrupt and context switching stats (by interrupts, context switches) (events per second).
+        - `-l`: Load average stats (1 min, 5 mins, 15 mins) (total system load multiplied by number of cores).
+        - `-c`: CPU stats (by system, user, idle, wait) (percentage of total).
+        - `--cpu-use`: Per-CPU usage (by CPU) (percentage).
+        - `-m`: Memory stats (by used, buffers, cache, free) (bytes).
+        - `-g`: Paging stats (by in, out) (count per second).
+        - `-s`: Swap stats (by used, free) (total).
+        - `-r`: Storage request stats (by read, write) (requests per second).
+        - `-d`: Storage throughput stats (by read, write) (bytes per second).
+        - `-n`: Network throughput stats (by recv, send) (bytes per second).
+        - `--socket`: Network socket stats (by total, tcp, udp, raw, ip-fragments)
+    - Useful plugins (metrics):
+        - `--net-packets`: Network request stats (by recv, send) (packets per second).
+    - Examples:
+        - General overview (CPU, RAM, ints/csws, disk, net): `dstat -tcmyrdn --net-packets 60`
+        - Network overview (CPU, ints/csws, net): `dstat -tcyn --net-packets 60`
+        - Process overview (CPU, RAM, ints/csws, paging, process, sockets): `dstat -tcmygp --socket 60`
+
+### File Systems and Logical Volume Managers
+
+- Partition disk: `gdisk <dev>` or `fdisk <dev>`
+- Create filesystem: `mkfs.<fs> <dev>`
+- Modify fstab:
+    - Test it with `mount -a` to make sure it doesn't have errors that may cause boot to fail.
+    - Run `systemctl daemon-reload` to avoid having systemd remount stuff that was removed from fstab or other weird shit.
+- Benchmark with IOzone:
+    - Install (Debian): `apt install iozone3`
+    - It uses the current dir.
+    - Test with various record sizes and file sizes: `iozone -a`
+    - Benchmark: `iozone -t1` (1 thread)
+    - Plot results: **TODO** It should be doable with gnuplot somehow.
+
+### Files
+
+- Search:
+    - By UID: `find / -user <UID>`
+    - Without a user: `find / -nouser`
+    - With setuid permission bit: `find / -perm /4000`
+    - Recursive search and replace: `find <dir> \( -type d -name .git -prune \) -o -type f -print0 | xargs -0 sed -i 's/123/456/g'`
+        - `-type d -name .git -prune` skips `.git` directories and can be excluded outside of git repos.
+- Usage:
+    - `du -sh <dirs>`
+    - K4DirStat (GUI) (package `k4dirstat`)
+- Shred files:
+    - `shred --remove --zero <file>`
+
+### Fun
+
+- Color text from STDIN: `lolcat`
+- `cowsay`
+- `fortune`
+
+### Hardware
+
+- Show hardware: `lshw`
+    - Run as root for more info.
+    - Specify `-X` to show GUI (requires `lshw-gtk`).
+- Show hardware topology: `lstopo` (requires hwloc)
+    - `lstopo` will try to present as a GUI. Use `lstopo-no-graphics` to force console output.
+- Show PCI devices: `lspci`
+- Show block devices: `lsblk`
+- Show USB devices: `lsusb`
+- Show CPUs: `lscpu`
+
+### Installations and Packages
+
+#### APT (Debian)
+
+- Find packages depending on the package: `apt rdepends --installed <package>`
+- Quickly add new repo: `add-apt-repository <repo-line`
+    - It will add the line to `/etc/apt/sources.list`, where you can manually remove it again.
+- Keys:
+    - List: `apt-key list`
+        - It will also show which file contains it.
+    - Remvoe key: `apt-key del <key-id>`
+        - The 8-digit hex key ID may either be found on `pub` line or as the last 8 hex digits on the continuation line.
+
+#### Pacman (Arch)
+
+- Full system upgrade: `pacman -Syu`
+- Search package: `pacman -Ss <package-name>`
+- Show package info: `pacman -Si <package>`
+- Install package: `pacman -S <packages>`
+    - Never use `-Sy` to avoid partial upgrades.
+- Remove package: `pacman -R <packages>`
+    - Remove orphans too: `-s`
+    - Purge configurations: `-n`
+
+### Network
+
+- Monitor usage:
+    - `nload <if>`
+    - `iftop -i <if>`
+    - `speedometer -t <if> -r <if> [...]`
+    - `dstat -tcyn --net-packets 60`
+- Monitor per-process usage:
+    - `nethog`
+- Test throughput:
+    - Internet: `speedtest` (from [speedtest.net](https://www.speedtest.net/apps/cli))
+    - Internal: `iperf3`
+- Show sockets (with `ss`):
+    - Example: `ss -tulpn`
+    - Note: `ss` replaces `netstat` and is mostly option compatible.
+    - Option `tu`: Include TCP and UDP sockets (no UNIX sockets).
+    - Option `l`: Include listening sockets (no client sockets).
+    - Option `p`: Show protocol (requires root).
+    - Option `n`: Don't translate port numbers to common service names.
+- Show misc. stats:
+    - Show kernel SNMP counters: `nstat`
+    - Show per-protocol stats: `netstat -s`
+- Bring interface up or down:
+    - Note: Your network manager probably has a more appropriate way to do this.
+    - Directly up or down interface: `ip link set dev <if> {up|down}`
+- Traffic shaping and link simulation:
+    - See `tc` to simulate e.g. random packet drop, random latencies, limited bandwidth etc.
+
+#### ip
+
+- General notes:
+    - Subcommands may be shortened (e.g. as `ip a` instead of `ip address`)
+    - For subcommands like `address` and `link`, it will default to show all elements if no further option is specified.
+- General options:
+    - Specified before the subcommand (e.g. `ip -c a`).
+    - `-c`: Show colored output.
+    - `-4` or `-6`: Show IPv4 or IPv6 addresses only.
+    - `-s`: Show stats (bytes, packets, errors, dropped, etc. for RX and TX).
+    - `-br`: Show brief with one line per interface (MAC address and status for `link`, addresses for `address`).
+    - `-o`: Show one line per interface (but all info unlike `-br`).
+    - `-j [-p]`: Print as JSON. Add `-p` for pretty printing.
+- Show L2/MAC addresses:
+    - Command: `ip link [show [<interface>]]`
+- Show L3/IP addresses:
+    - Command: `ip address [show [<interface> [scope <scope>]]]`
+    - Argument `scope global`: Only show global addresses (excludes localhost/`host`, link-local/`link`, etc.).
+- Show neighbors:
+    - Command: `ip neighbor`
+- Show routes:
+    - Command: `ip route`
+- Show multicast addresses:
+    - Command: `ip maddress`
+- Show multicast routes:
+    - Command: `ip mroute`
+
+#### tcpdump
+
+- Typical usage: `tcpdump -i <interface> -nn -v [filter]`
+- Options:
+    - `-w <>.pcap`: Write to capture file instead of formatted to STDOUT.
+    - `-i <if>`: Interface to listen on. Defaults to a random-ish interface.
+    - `-nn`: Don't resolve hostnames or ports.
+    - `-s<n>`: How much of the packets to capture. Use 0 for unlimited (full packet).
+    - `-v`/`-vv`: Details to show about packets. More V's for more details.
+    - `-l`: Line buffered more, for better stability when piping to e.g. grep.
+- Filters:
+    - Can consist of complex logical statements using parenthesis, `not`/`!`, `and`/`&&` and `or`/`||`. Make sure to quote the filter to avoid interference from the shell.
+    - Protocol: `ip`, `ip6`, `icmp`, `icmp6`, `tcp`, `udp`, ``
+    - Ports: `port <n>`
+    - IP address: `host <addr>`, `dst <addr>`, `src <addr>`
+    - IPv6 router solicitations and advertisements: `icmp6 and (ip6[40] = 133 or ip6[40] = 134)` (133 for RS and 134 for RA)
+    - IPv6 neighbor solicitations and advertisements: `icmp6 and (ip6[40] = 135 or ip6[40] = 136)` (135 for NS and 136 for NA)
+    - DHCPv4: `ip and udp and (port 67 and port 68)`
+    - DHCPv6: `ip6 and udp and (port 547 and port 546)`
+
+### Memory
+
+- NUMA stats:
+    - `numastat` (from package `numactl`)
+
+### Performance and Power Efficiency
+
+- Set the CPU frequency scaling governor mode:
+    - High performance: `echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor`
+    - Power save: `echo powersave | ...`
+- Show current core frequencies: `grep "cpu MHz" /proc/cpuinfo | cut -d' ' -f3`
+
+### Profiling
+
+- `time` (timing commands):
+    - Provided both as a shell built-in `time` and as `/usr/bin/time`, use the latter.
+    - Typical usage: `/usr/bin/time -p <command>`
+    - Options:
+        - `-p` for POSIX output (one line per time)
+        - `-v` for interesting system info about the process.
+    - It give the wall time, time spent in usermode and time spent in kernel mode.
+- `strace` (trace system calls and signals):
+    - In standard mode, it runs the full command and traces/prints all syscalls (including arguments and return value).
+    - Syntax: `strace [options] <command>`
+    - Useful options:
+        - `-c`: Show summary/overview only. (Hints at which syscalls are worth looking more into.)
+        - `-f`: Trace forked child processes too.
+        - `-e trace=<syscalls>`: Only trace the specified comma-separated list of syscalls.
+
+### Security
+
+- Show CPU vulnerabilities: `tail -n +1 /sys/devices/system/cpu/vulnerabilities/*`
+- Generate XKCD-style (multi-word) passwords (using package `xkcdpass`): `xkcdpass`
+- Generate SHA cryptographical hashes: `sha{256,512} <files>`
+- Check PGP signature of file (using GPG):
+    1. Get the data file, a detached/separate signature file (`.sig`) for the data file, and the publisher's key (manually downloaded or through a key server). The Data file and sig may be from untrusted sources (like a download mirror).
+    1. (Alternative 1) Import a downloaded keyfile:
+        1. Note: Download the publisher's key file (`.asc`) and its fingerprint from a trusted source.
+        1. Show the details and fingerprint of the key: `gpg --show-keys <keyfile>`
+        1. (Recommended) Compare the fingerprint from the keyfile from the one on the publisher's website or whatever (some trusted source).
+        1. Make sure the `uid` of the key is recognizable wrt. the intended use.
+        1. Import the key: `gpg --import <keyfile>`
+    1. (Alternative 2) Import the keyfile from a key server:
+        1. Note: Import the publisher's key from a key server, given a server URL and fingerprint. The fingerprint must be from a trusted source.
+        1. Inspect the key before importing: **TODO**
+        1. Make sure the `uid` of the key is recognizable wrt. the intended use.
+        1. Download the key: `gpg [--keyserver <url>] --recv-keys <key-id>`
+    1. Finally, verify the data file using the detached signature and imported key: `gpg --verify <sigfile> <datafile>`
+
+### Storage
+
+- Test read speed: `hdparm -t <dev>` (safe)
+- Show IO load for devices: `iostat [-dxpm] [-t] [interval]`
+    - `-d`: Show only device usage.
+    - `-x` and `-p`: Include extended attributes and partitions.
+    - `-t` and interval: Show timestamp and repeat every x seconds.
+- Show IO usage for processes: `iotop -o [-a]`
+
+### System
+
+- Version info:
+    - Release info files:
+        - Debian (and Ubuntu): `/etc/debian_version`
+        - RHEL: `/etc/redhat-release`
+        - CentOS: `/etc/centos-release`
+    - General release info: `uname -a`
+    - Slightly more distro-specific release info: `lsb_release -a`
+- Monitor system load:
+    - `uptime`
+    - `iostat [-c] [-t] [interval]`
+- Monitor processes:
+    - `ps` (e.g. `ps aux` or `ps ax o uid,user:12,pid,comm`)
+- Monitor a mix of things: See the "general monitoring" section.
+- Monitor interrupts:
+    - `irqtop`
+    - `watch -n0.1 /proc/interrupts`
+- Run command with high or low CPU priority:
+    - Command: `nice -n<n> <cmd>` (`-20 <= n <= 19`)
+    - The nice value goes from -20 (highest priority) to 19 (lowest priority), with 0 as the default priority.
+    - The nice value is inherited by child processes (meaning forking processes maintains the nice value it started with).
+    - Use `renice` to change the value.
+    - Use `ionice` to set the I/O scheduler and scheduler-specific priority.
+- Stress test with stress-ng:
+    - Install (Debian): `apt install stress-ng`
+    - Stress CPU: `stress-ng -c $(nproc) -t $((10*60))` (use all CPU threads for 10 minutes)
+- Chroot into other Linux installation:
+    1. Note: Used to e.g. fix a broken install or reset a user password from a USB live ISO.
+    1. Mount the root partition: `mount /dev/sda2 /mnt` (example)
+    1. Mount e.g. the EFI partition: `mount /dev/sda1 /mnt/boot/efi` (example)
+    1. Mount system stuff:
+        1. `mount -t proc proc /mnt/proc`
+        1. `mount -t sysfs sys /mnt/sys`
+        1. `mount -t bind /dev /mnt/dev`
+    1. Enter jail: `chroot /mnt [/bin/bash]`
+        - Specifying the shell to use, e.g. `/bin/bash`, may be necessary.
+    1. Do stuff.
+    1. Exit jail: `exit`
+
+## Tasks
+
+### Burn Windows ISO (Ubuntu)
+
+1. Install the graphical application `woeusb` from `ppa:nilarimogard/webupd8`.
+
 {% include footer.md %}

config/media/vlc.md

@@ -82,8 +82,9 @@ breadcrumbs:
 ## View Stream
 
 - View stream: `vlc <proto>://<host>[:port][/path]`
-- Specify `--network-caching=100` (milliseconds) to reduce network buffering causing delay (default to 1 second).
-- Use `cvlc` (Linux) or specify `-I dummy --dummy-quiet` to not use the full GUI.
+    - RTSP (example): `vlc rtsp://<host>:554 --rtsp-user=$rtsp_username --rtsp-pwd=$rtsp_password`
+- Specify `--network-caching=100` (milliseconds) to reduce network buffering causing delay (defaults to 1000ms).
+- Use `cvlc` (Linux) or specify `-I dummy --dummy-quiet` (Windows) to not use the full GUI.
 - Specify `--fullscreen` to start in full screen.
 
 ## Examples

config/media/youtube-dl.md

@@ -13,14 +13,18 @@ A tool for downloading videos from a variety of site (not just YouTube).
 - [Homepage](http://ytdl-org.github.io/youtube-dl/)
 - [Repo](https://github.com/ytdl-org/youtube-dl)
 
-## Usage
+## Installation
 
-- Run in Docker:
+- Docker:
     - Using ([wernight's image](https://github.com/wernight/docker-youtube-dl)).
     - Command prefix: `docker run --rm -v//$PWD:/downloads wernight/youtube-dl <...>`
-- Run binary:
+- Binary:
+    - The one in typical package repos is typically quite outdated (even for Arch/the AUR).
     - Find the download instructions in the repo.
-    - Install "ffmpeg" to allow downloading best quality audio and video: `apt install ffmpeg`
+    - Install `ffmpeg` to allow downloading best quality audio and video.
+
+## Usage
+
 - Download single video: `youtube-dl -c <URL>`
     - `-c`/`--continue` to re-run the command if it previously failed during download.
 - Download full channel or playlist: `youtube-dl -qiwc --no-warnings [-o <format>] <URL>`
@@ -40,7 +44,8 @@ A tool for downloading videos from a variety of site (not just YouTube).
 
 ## Examples
 
-- YouTube video/xyz in Docker: `docker run --rm -v//$PWD:/downloads wernight/youtube-dl -iwc -f bestvideo+bestaudio --cookie ~/cookies.txt -o "%(uploader)s (%(upload_date)s) - %(title)s [%(id)s].%(ext)s"`
+- Docker: `docker run --rm -v//$PWD:/downloads wernight/youtube-dl <...>`
+- YouTube video: `youtube-dl -iwc -f bestvideo+bestaudio --cookie ~/cookies.txt -o "%(uploader)s (%(upload_date)s) - %(title)s [%(id)s].%(ext)s"`
 - YouTube video/channel/playlist w/ cookie: `youtube-dl -iwc -f bestvideo+bestaudio --cookie ~/cookies.txt -o "%(uploader)s (%(upload_date)s) - %(title)s [%(id)s].%(ext)s" <url>`
 
 ## Troubleshooting

config/pc/applications.md

@@ -265,7 +265,7 @@ This is my ZSH setup preference, using Oh-My-ZSH with the Powerlevel10k theme an
 1. Make zprofile include profile (to avoid breaking certain things):
     1. In `~/.zprofile`, add: `emulate sh -c "source /etc/profile"`
 1. Setup plugins:
-    1. In `.zshrc`, set e.g. `plugins=(git docker docker-compose golang rust cargo rustup)`.
+    1. In `.zshrc`, set e.g. `plugins=(git docker docker-compose golang rust)`.
 1. Setup syntax highlighting plugin:
     1. Clone it: `git clone https://github.com/zsh-users/zsh-syntax-highlighting.git ~/.oh-my-zsh/custom/plugins/zsh-syntax-highlighting`
     1. Add `zsh-syntax-highlighting` it to `plugins` in `.zshrc`.

index.md

@@ -12,7 +12,6 @@ Random collection of config notes and miscellaneous stuff. _Technically not a wi
 
 - [General](/config/general/general/)
 - [Linux General Notes](/config/general/linux-general/)
-- [Linux Examples](/config/general/linux-examples/)
 - [Computer Testing](/config/general/computer-testing/)
 
 ### Authentication, Authorization and Accounting (AAA)