vault backup: 2025-01-19 21:14:51

11 files changed, 0 insertions, 212 deletions

diff --git a/3 resources/linux/APT.md b/3 resources/linux/APT.md
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-#linux #packages #how-to
-
----
-reinstall packages:
-`apt reinstall <pkg>`
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diff --git a/3 resources/linux/Definitions.md b/3 resources/linux/Definitions.md
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index c0ca4dd..0000000
--- a/3 resources/linux/Definitions.md
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-#linux #definitions 
-
----
-NBP = Network Bootstrap Program
-PXE = Preboot Execution  Environment
-NIC = Network Interface Card
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diff --git a/3 resources/linux/Device drivers.md b/3 resources/linux/Device drivers.md
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index 95f1a75..0000000
--- a/3 resources/linux/Device drivers.md
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@@ -1,22 +0,0 @@
-#linux #devices 
-
----
-major, minor numbers
-major = driver (used by kernel when opening device to dispatch to correct driver)
-minor = used by driver to differentiate device(s)
-
-after disk the major, minor numbers are shown:
-```
-[jasras@n04.compute.vps2-lej1 ~]$ ls -l /dev/dm-*
-brw-rw---- 1 root disk 253,  0 Oct 25 10:10 /dev/dm-0
-brw-rw---- 1 root disk 253,  1 Oct 25 10:11 /dev/dm-1
-brw-rw---- 1 root root 253, 11 Oct 28 19:58 /dev/dm-11
-brw-rw---- 1 root root 253, 12 Oct 28 19:58 /dev/dm-12
-```
-
-available devices: `cat /proc/devices`
-
-character devices vs block devices; what is the difference?
-
----
-[oreilly-device-drivers](https://www.oreilly.com/library/view/linux-device-drivers/0596000081/ch03s02.html)
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diff --git a/3 resources/linux/Device mapper.md b/3 resources/linux/Device mapper.md
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index 059a0d1..0000000
--- a/3 resources/linux/Device mapper.md
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-#linux #device-mapper
-
----
-Device mapper is a kernel driver to map physical block devices to virtual ones; this means that for example we can have many physical devices be represented by a single virtual one (linear mapping).
-
-How does it work?
-[[1 projects/Inwerken Mohammed/TODO]]
-What is its function in relation to multipath?
-
-Logical devices using device-mapper can be managed using `man 8 dmsetup`
-```
-[jasras@n04.compute.vps2-lej1 ~]$ sudo dmsetup info 3600a098038314d736724566a67346538
-Name:              3600a098038314d736724566a67346538
-State:             ACTIVE
-Read Ahead:        256
-Tables present:    LIVE
-Open count:        1
-Event number:      3
-Major, minor:      253, 12
-Number of targets: 1
-UUID: mpath-3600a098038314d736724566a67346538
-```
-
-If dmsetup cannot remove a device because a process still has it open, but lsof does not show any processes that open it, use `-f` which replaces the device with a fake that rejects all I/O.
-
----
-[device-mapper](https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/logical_volume_manager_administration/device_mapper#device_mapper)
-[dmsetup](https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/logical_volume_manager_administration/dmsetup#dmsetup)
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diff --git a/3 resources/linux/LSOF.md b/3 resources/linux/LSOF.md
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index 5a3aa95..0000000
--- a/3 resources/linux/LSOF.md
+++ /dev/null
@@ -1,69 +0,0 @@
-#linux #how-to 
-
----
-
-```
-lsof -p 1111 # show open files for this PID
-lsof /path/to/file # show which process has this open
-```
-
-A usage in the wild; using lsof to find the qemu process for a specific base image and using that to get instance name and disk path:
-```
-lsof -F p {{ item['path'] }} | cut -b 2- | head -1 | xargs ps | grep -oP '(instance\\-[a-z0-9]+)|(\\/var\\/lib\\/nova\\/instances\\/[a-z0-9\\-]+\\/disk)' | uniq
-```
-
-(man lsof: search "OUTPUT FOR OTHER PROGRAMS")
-output for other programs
-```
-specify -F
-These are the fields that lsof will produce.  The single character listed first is the field identifier.
-            a    file access mode
-            c    process command name (all characters from proc or
-                 user structure)
-            C    file structure share count
-            d    file's device character code
-            D    file's major/minor device number (0x<hexadecimal>)
-            f    file descriptor (always selected)
-            F    file structure address (0x<hexadecimal>)
-            G    file flaGs (0x<hexadecimal>; names if +fg follows)
-            g    process group ID
-            i    file's inode number
-            K    tasK ID
-            k    link count
-            l    file's lock status
-            L    process login name
-            m    marker between repeated output
-            M    the task comMand name
-            n    file name, comment, Internet address
-            N    node identifier (ox<hexadecimal>
-            o    file's offset (decimal)
-            p    process ID (always selected)
-            P    protocol name
-            r    raw device number (0x<hexadecimal>)
-            R    parent process ID
-            s    file's size (decimal)
-            S    file's stream identification
-            t    file's type
-            T    TCP/TPI information, identified by prefixes (the
-                 `=' is part of the prefix):
-                     QR=<read queue size>
-                     QS=<send queue size>
-                     SO=<socket options and values> (not all dialects)
-                     SS=<socket states> (not all dialects)
-                     ST=<connection state>
-                     TF=<TCP flags and values> (not all dialects)
-                     WR=<window read size>  (not all dialects)
-                     WW=<window write size>  (not all dialects)
-                 (TCP/TPI information isn't reported for all supported
-                   UNIX dialects. The -h or -? help output for the
-                   -T option will show what TCP/TPI reporting can be
-                   requested.)
-            u    process user ID
-            z    Solaris 10 and higher zone name
-            Z    SELinux security context (inhibited when SELinux is disabled)
-            0    use NUL field terminator character in place of NL
-            1-9  dialect-specific field identifiers (The output
-                 of -F? identifies the information to be found
-                 in dialect-specific fields.)
-
-```
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diff --git a/3 resources/linux/Users.md b/3 resources/linux/Users.md
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index 885a7cc..0000000
--- a/3 resources/linux/Users.md
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@@ -1,22 +0,0 @@
-#linux #user-management 
-
-Change uid/gid of user
-`usermod -u newnumber user`
-`groupmod -g newnumber user`
-
-File permissions in homedir will be automatically updated; file perms outside home dir will not be automatically updated.
-
-Finding files of a specific user, and printing their uid/gid;
-`sudo find / -user 4109 -printf '%p %u(%U) %g(%G)\n'`
-
-To change only the group: `chgrp`.
-
-Or using find to chmod/chgrp:
-`sudo find / -user 4109 -group 4109 -exec chmod 998:998 {} \;`
-`sudo find / -group 4109 -exec chgrp 998 {} \;`
-
-Dirty way to find "system users" (uid < 999) - note that this is not fool-proof, it also lists groups
-`getent passwd | grep -oP '\b[0-9]{3}\b' | uniq | sort`
-
----
-https://www.cyberciti.biz/faq/linux-change-user-group-uid-gid-for-all-owned-files/
diff --git a/3 resources/linux/Watch.md b/3 resources/linux/Watch.md
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index 0c167b7..0000000
--- a/3 resources/linux/Watch.md
+++ /dev/null
@@ -1,4 +0,0 @@
-#linux #how-to 
-
----
-`watch (1)` periodically executes the executable on argv. It can be used to reload the output of a command, like `sudo watch ovs-dpctl dump-flows` .
diff --git a/3 resources/linux/filesystems/Tmpfs.md b/3 resources/linux/filesystems/Tmpfs.md
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index b8fe839..0000000
--- a/3 resources/linux/filesystems/Tmpfs.md
+++ /dev/null
@@ -1,16 +0,0 @@
-#linux #filesystem
-
----
-Is a [[virtual filesystem]] that is stored in memory; it uses both RAM and swap space.
-> Kernel option: CONFIG_TMPFS
-
-`mount -t tmpfs source target`
-
-A tmpfs can only grow to 50% of RAM avail. unless overridden with size=nbytes mount option. 
-Only consumes RAM for actual usage.
-Data is ephemeral/volatile.
-
-Mount stacking: mount over existing /tmp, to improve speed of apps using alot of tmp files, then unmount to delete data.
-
-Kernel uses tmpfs for [[system v shared memory]] and [[shared anonymous memory mappings]].
-`/dev/shm` or `/run/shm`: [[glibc]] of [[POSIX]] shared memory and [[POSIX]] semaphores.
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diff --git a/3 resources/linux/networking/DHCP.md b/3 resources/linux/networking/DHCP.md
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index e7e8e38..0000000
--- a/3 resources/linux/networking/DHCP.md
+++ /dev/null
@@ -1,5 +0,0 @@
-#networking #linux 
-
----
-Dynamic Host Configuration Protocol
-Allows hosts dynamically receive an IP address.
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diff --git a/3 resources/linux/networking/IP masquerade.md b/3 resources/linux/networking/IP masquerade.md
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index 2ccc8e6..0000000
--- a/3 resources/linux/networking/IP masquerade.md
+++ /dev/null
@@ -1,17 +0,0 @@
-#linux #networking 
-
----
-A function in the kernel that allows guests with internal/private IPs to access the internet by using the hosts' public IP similar to 1 to many NAT.
-
-Differences with Proxy, IP Masq, NAT:
-
-**Proxy**
-Requires special configuration on internal client side. Can be used for caching.
-
-**IP Masq**
-A form of NAT used primarily in Linux devices. Translates IP address and uses the connection tracking table and ports to map responses back to the internal connection.
-
-**NAT**
-Has different types with different use-cases.
-Static NAT: 1-1 mapping of pub/private IP. Dynamic NAT: pool of pub ips to dynamically map private IPs to based on availability. 
-PAT (Port): similar to IP Masq; 1-many using ports.
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diff --git a/3 resources/linux/networking/PXE.md b/3 resources/linux/networking/PXE.md
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index d5fe4d1..0000000
--- a/3 resources/linux/networking/PXE.md
+++ /dev/null
@@ -1,18 +0,0 @@
-#linux #pxe
-
----
-The NBP is a bootloader that is obtained via the network typically via [[TFTP]]. It handles setting up an environment in which an OS can run or install. For example, it displays a boot menu and downloads the kernel images. It sets up hardware, for example the [[NIC]]s.
-
-PXE boot process:
-1. Modified [[DHCP]] request: request to include boot information (PXE boot request).
-2. Process DHCP response which includes an IP address of [[TFTP]] server and filename of [[NBP]].
-3. Download NBP over TFTP.
-4. NBP executes
-	1. Loads additional stuff over network, like kernel images.
-	2. Handles the boot menu
-5. Kernel takes over boot process and potentially downloads additional files required to complete booting.
-
-Popular NBP's:
-- PXELINUX
-- iPXE
-- GRUB2