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Windows Development Software for you local human laptop
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HDMI and Display Port versions:
In general, lower refresh rates the same, higher + variable fresh rates:
dp 1.4 > hdmi 2.0
hdmi 2.1 > dp 1.4
dp 2.1 > hdmi 2.1
Capabilities depends on graphics card, monitor, cable
Good read, overview of current hdmi + display port versions
source https://www.tomshardware.com/features/displayport-vs-hdmi-better-for-gaming
nvidia RTX 3000/4000 and amd RX 6000/7000: hdmi 2.1
nvidia RTX 3000/4000 and amd RX 6000: dp 1.4
amd RX 7000: dp 2.1
usbc 4, thunderbolt: dp 1.2 to 2.1
source https://www.cablematters.com/Blog/HDMI/displayport-vs-hdmi
HDMI HDMI HDMI DP DP DP DP
1.4 2.0 2.1 1.2 1.3 1.4 2.0
1080p @ 120Hz ✅ ✅ ✅ ✅ ✅ ✅ ✅
1440p @ 30Hz ✅ ✅ ✅ ✅ ✅ ✅ ✅
1440p @ 60Hz ✅ ✅ ✅ ✅ ✅ ✅ ✅
1440p @ 120Hz ❌ ✅ ✅ ✅ ✅ ✅ ✅
4k @ 30Hz ✅ ✅ ✅ ✅ ✅ ✅ ✅
4k @ 60Hz ❌ ✅ ✅ ✅ ✅ ✅ ✅
4k @ 120Hz ❌ ❌ ✅ ❌ ✅ ✅ ✅
8k @ 30Hz ❌ ❌ ✅ ❌ ✅ ✅ ✅
8k @ 60Hz ❌ ❌ ✅ ❌ ❌ ✅ ✅
8k @ 120Hz ❌ ❌ ✅ ❌ ❌ ❌ ✅
HDR ❌ ✅ ✅ ❌ ❌ ✅ ✅
source https://www.cablematters.com/Blog/HDMI/displayport-vs-hdmi
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Some useful Linux commands
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cat
cat [file]
- cat = dump file contents to terminal; ls -l to ensure small file
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df
df -h
- df = show disks space per partition
- / = separate volume/disk for root os, logs
- /data = separate volume/disk for websites, apps
- -h = human readable size
- df = show disks space per partition
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grep
grep [search] [files]
- grep = filter results, look for patterns in files
- Example: grep Error *.log
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htop
htop
- htop = top list of processes, nicely colored; can sort, filter
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kill
kill [pid]
- kill = force stop/kill a process; only use for 'hung' process
- [pid] = pid from
ps auxlist
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ls
ls -lhtr [dir]
- ls = list contents of directory
- -l = details
- -h = human readable sizes
- -t = sort by time
- -r = reverse sort, so new shows at bottom
- -1 = just list names in a single column
- Example: ls -lhtr logs/*
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ps
ps aux
- ps = process list
- a = all, including other users
- u = user format
- x = register format
- Example: ps aux | grep nginx
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reboot
sudo reboot
- reboot = reboot server; should not be needed; restart individual services
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systemctl
sudo systemctl [action] [process]
- systemctl = manage services such as nginx, php-fpm
- Example: sudo systemctl status nginx
- Example: sudo systemctl restart nginx
- Example: sudo systemctl status php-fpm
- Example: sudo systemctl restart php-fpm
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tail
tail -f -n50 [file]
- tail = returns the last few lines of a file
- -n# = number of lines
- -f = follow, useful for tailing an active log file
- Example: tail -f logs/app.log
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vim
vim [file]
- vim, vi = text editor; ls -l to ensure small file
- arrow keys = move cursor
- shift G = go to end of file
- ctrl u = page up
- ctrl d = page down
- /[patttern] = search for pattern
- esc = get out of most vi modes
- :q = quit
- :q! = quit without writing
- :wq = write, quite
- note, if quit a SSH session with a file vi-ed/open, be sure to SSH in again and cleanup the vi auto backup [file]~; vi-ing the original file again will prompt you about
- Example: sudo vim /var/log/messages
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Some general tips for researching a slow or unresponsive app or system
Starting checklist
- SSH to EC2/server
- Check disk space
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df -h
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- Check processes
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htop
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ps aux
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- Check app logs
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cd app/
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ls -lhtr logs/
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vim [log]
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- Check system logs
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ls -lhtr /var/log/
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tail -f -n50 /var/log/messages
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- Check disk space
- SQL Processes
- DB Gui: Tools -> Server Monitor -> SQL
- Check AWS console
- EC2 list
- Monitoring
- RDS list
- Monitoring
- Performance Insights
- Cloud Watch
- Alarms
- Monitoring
- EC2 list
- App specific
- grep (Find in Files, Search)
- grep cron for script name
- grep code for database table names, fields
- grep [everything]
- Check logs
- Often located relative to script, in logs/ or log/
- Can be also be in /var/log/[app dir]/
- grep (Find in Files, Search)
Logs
App logs
Locations will vary
Some apps may be relative to their PHP (or other language) files, often log/ or logs/
Some cron or processing logs may be in /var/log/[process dir]/
Note, log locations should be consistent to facilitate finding them.
Web Server logs
On some errors, such as fatal or configuration errors, PHP (or other language) info is outputted to the web server logs, such as Nginx
nginx is the process name
PHP runs as a separate process, php_fpm
ls -lhtr /var/log/nginx
tail -n50 /var/log/nginx/[site]_error.log
tail -f /var/log/nginx/[site]_error.log
ls -lhtr /var/log/php-fpm/
ls -lhtr /var/log/
You may need to login as sudo user ec2-user to view system logs
Common log for OS messages
sudo vim /var/log/messages
Common log for login, security messages
sudo vim /var/log/secure
Web Server Config
Nginx is a common web server
You can grep for dns or web directories to know
- server_name = what dns is being used
- root = which directory a site is being hosted from
- error_log = where the log files are
grep [site] /etc/nginx/sites.d/*
vim /etc/nginx/sites.d/[site].conf
server_name [site].com;
set $env "dev";
set $app_dir "[repo name]";
root /data/sites/$env/$app_dir/public/;
access_log /var/log/nginx/[site].com_access_log;
error_log /var/log/nginx/[site].com_error_log error;
Cron
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * user-name command to be executed
# EXAMPLE CRON
*/10 * * * * [app user] /usr/bin/php -q /[process dir]/[script] [args if any] &>> \
/var/log/[process dir]/[script].log
- ensure specify the app user
- &>> [log] is shorthand for >> [log] 2&>>1
- > = overwrite
- >> = append
- 2&>1 = redirect errors to standard out eg capture errors in log
- compare to other crons to keep a consistent pattern
System crons
ls -lhtr /etc/cron.d/
Preferred
Crons in /etc/cron.d/ allow for custom runtimes. A cron file per concept/process/logical grouping should be created, and can contain multiple scripts/commands.
Note, there are other potential system crons such as /etc/cron.daily which will run crons .. daily, but without the flexibility of specify when during the day they run; cron.daily often runs at 2am or 3am depending on the OS. Only use /etc/cron.d/
User crons
crontab -l
view cron of current user
crontab -e
edit cron of current user
Not recommended
Crons can also be attached to a user. User crons are not easily accessible and are stored in one file per user, making a large number of crons harder to manage, and overly easy to delete (crontab -r = poof gone).
To manually backup a users cron
cd ~
crontab -l > cron_[Ymd].txt
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