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fundamentals/basics.md

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+# Processes
+
+Process id 1 is systemd.  All other processes are child processes.
+
+> ps -sH
+
+This has every process on the system, and -H shows the hierarchy.  This can be piped to less to view easily.
+
+> ps -u ghost
+
+Looking at processes spawned from user 'ghost'.
+
+> ps -e --forest
+
+Like tree, but more.
+
+> ps -sfH
+
+The fucking lot.
+
+All of this is from /proc, which is a direct line to the kernel.  Commands like `free', `top' et c. pulls from /proc.
+
+# Top
+
+In `top' we can take the pid and then press `k' in order to kill that process.
+
+# check what's going on with qutebrowser
+
+> ps aux | grep qutebrowser
+
+# Check open ports
+sudo netstat -tulpn
+
+#Check that udev process
+systemctl status udev
+
+# Show net interface
+> ip addr show
+
+This can also take arguments, such as the name of an interface.
+
+# Find
+
+> find . -name 'bob cv'
+
+Find file 'bob cv'
+
+> find . -size +7G
+
+Find files of 7Gig or more.
+
+> find -name *hidden* -type l
+
+Find a symbolic link containing 'hidden' in the name.
+
+> find -name *txt -delete
+
+Delete all files from here of the *txt type.
+
+> find -type d -empty
+
+Find empty directories.
+
+> find . mtime 50
+
+Find all file modified precisely 50 days ago.  There's also:
+
+* -mtime +20
+   * file modified more than 20 days ago.
+* -atime -13
+   * file *accessed* less than 13 days ago.
+* -cmin 20
+   * file *modified* 20 minutes ago.
+* -mmin +70
+   * files modified more than 70 minutes ago.
+
+
+# Logs
+
+> cat /var/logs/auth.log | grep fail
+
+
+# Files
+
+> file example.txt
+
+This shows info about a file.
+
+# Further reading
+
+[Hund](https://hund0b1.gitlab.io/2019/02/11/a-collection-of-handy-ways-of-manipulating-text-in-bash.html) has some fantastic examples.
+
+