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LFCS Study Outline 2015.02.28
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| * LFCS Domains 2015.02 | |
| Note - the domains will change somewhat in March 2015. SW RAID | |
| with mdadm will be removed | |
| ** The Command Line | |
| *** Editing text files on the CLI | |
| Covers the use of the basic text editors nano and gedit as well | |
| as the advanced editors _vi_ and _emacs_ | |
| - nano | |
| simple CLI-based text editor | |
| - gedit | |
| simple GUI-based text editor | |
| - *vi/vim* | |
| - invocation | |
| + vi -r myfile :: start vi and edit myfile in recovery mode | |
| after a system crash - vim stores your changes in a swap | |
| file. Using the original file plus the swap file, you can | |
| mostly recover your work. | |
| + vi myfile :: edit myfile with vi | |
| - _command mode_ | |
| initial mode that vim starts in | |
| - movement | |
| + hjkl :: Left Down Up Right | |
| + H :: move to top of screen | |
| + L :: move to bottom of screen | |
| + 0 :: move to beginning of line | |
| + $ :: move to end of line | |
| + :0 or 1G or gg :: move to beginning of file | |
| + :n or nG :: move to line 'n' | |
| + :10 :: move to 10th line | |
| + 10G :: move to 10th line | |
| + :$ or G :: move to last line in file | |
| + C-f :: move forward one page | |
| + C-b :: move back one page | |
| + /pattern :: forward search for 'pattern' | |
| + ?pattern :: reverse search for 'pattern' | |
| + n :: move to next occurrence of search pattern | |
| + N :: move to previous occurrence of search pattern | |
| + C-g :: show position and line no; type _nG_ to go to | |
| line number `n` | |
| - editing | |
| + a :: append text after cursor | |
| + A :: append text at end of current line | |
| + I :: insert text at the beginning of current line | |
| + i :: insert text before cursor | |
| + o :: start new line below current line, insert text | |
| + O :: start new line above current line, insert text | |
| + Nx :: delete N chars, starting at current position | |
| + dw :: delete the word at the current position | |
| + D or d$ :: delete the rest of the current line | |
| + Ndd or dNd :: delete N lines | |
| + u :: undo the previous operation | |
| + C-R :: redo | |
| + yy :: yank(copy) the current line and put in buffer | |
| + Nyy or yNy :: yank N lines and put in buffer | |
| + p :: put after the current line | |
| + P :: put before the current line | |
| - _insert mode_ | |
| from command mode, press 'i' to enter Insert mode | |
| - _line mode_ | |
| from command mode, press ':' to enter Line mode | |
| + :r file2 :: read in file2 and insert at current position | |
| + :w :: write to the current file in buffer | |
| + :w myfile :: write out the file to myfile | |
| + :w! file2 :: overwrite file2 | |
| + :x :: exit vi and write out modified file | |
| + :wq :: exit vi and write out modified file | |
| + :ZZ :: same as ':x', ':wq' save and exit vi | |
| + :q! :: quit vi without saving changes | |
| + external commands | |
| + :! wc % :: word count of current file (%) | |
| + :sh cmd :: open an external cmd shell; upon exit | |
| resume vi session | |
| + %!fmt :: run current file through fmt and return results | |
| - *emacs* | |
| As emacs is our editor of choice, we know most of the | |
| commands required for daily usage. We are only making note | |
| of those cmds were weren't aware of previously | |
| - C-o :: insert a blank line | |
| - C-@ :: same as C-space (set mark) | |
| - M-g-g-n :: goto line n | |
| *** Manipulating text files on the CLI | |
| - I/O Redirection | |
| - read from '<' | |
| - write to '>' | |
| - append to '>>' | |
| - Viewing files | |
| - cat :: list file on stdout (no scrollback) | |
| - tac :: list file on stdout in reverse order (no scrollback) | |
| - less :: useful for viewing larger files as it provides scrollback | |
| pauses at each screenful of text | |
| - head :: print first 10 lines of a file by default | |
| - tail :: print last 1o lines of a file by default | |
| - head -n X | tail -n Y :: view a range of lines from text on stdin | |
| + _head -n 22 | tail -n 11_ | |
| Display from lines 12 to 22, inclusive. Note that _tail_ must | |
| show the last *11* lines (22,21,20,19,18,17,16,15,14,13,12) | |
| starting from 22 in order for line 12 to be included. | |
| 0-9: 10 numbers, 0-10: 11 numbers, 12-22: 11 numbers | |
| - Manipulating Text | |
| - cat :: concatenate - read, print, join, view files | |
| + cat file1 file2 :: concatenate multiple files and display output | |
| + cat file1 file2 > newfile :: concatenate multiple files and | |
| redirect output to newfile (overwrites) | |
| + cat file >> file2 :: append file to end of file2 | |
| + cat > file :: interactive mode; redirect stdin to file | |
| Ctrl-d to terminate input | |
| + cat >> file :: interactive mode; append stdin to file | |
| Ctrl-d to terminate input | |
| + *tac* can be used in all the same ways as above as it has | |
| the same syntax as _cat_ | |
| - echo :: displays (echoes) text on stdout | |
| is often used to redirect text to files and also display the | |
| value of variables | |
| + echo -e :: use escaped char sequences like '\n' and '\t' | |
| + echo string > file :: write string to file | |
| + echo string >> file :: append string to file | |
| + echo $var :: print value of env. variable | |
| - sed :: stream editor | |
| filter and substitute text from an input source and move | |
| to stdout or an output stream | |
| - invocation | |
| + sed -e cmd <file> :: specify editing cmd, operate on | |
| file and send result to stdout | |
| + sed -f scriptfile <file> :: specify a script containing | |
| sed cmds, operate on file, send result to stdout | |
| + sed s/pattern/replace_str/ file :: substitute 1st string | |
| occurrence in a line | |
| + sed s/pattern/replace_str/g file :: subtitute _pattern_ with | |
| _replace_str_ globally (similar to vi _:s/foo/bar/g_) | |
| + sed 1,3s/pattern/replace_str/g file :: substitute all string | |
| occurrences in lines 1 through 3 | |
| + sed -i s/pattern/replace_str/g file :: edit files in-place | |
| saves changes for string substitution in the same file; this | |
| option is not recommended b/c it is irreversible; if you | |
| absolutely must overwrite the original, '>' to a new file, | |
| verify changes, and then '> originalFile' | |
| ** Filesystem and Storage | |
| - *Archiving and Compressing files and directories* | |
| + Compressing files | |
| _tar cvf(z) archive.tar(.gz) file1 file2 file3_ | |
| + Compressing directories | |
| _tar cvf(z) archive.tar(.gz) /path/to/dir_ | |
| When you run this command, make sure your /pwd/ is not | |
| the directory you are trying to archive! | |
| - *Assembling partitions as RAID devices* | |
| 1. Examine the drives which will compose the array | |
| (Assume we have two drives, sdb and sdc) | |
| _mdadm --examine /dev/sd[b-c]_ | |
| We want to make sure that there is no existing RAID | |
| on the two disks ('no md superblock') | |
| 2. Create partitions with fdisk | |
| _fdisk /dev/sdb_ (and later for /dev/sdc) | |
| + n :: create new partition ('1' for primary) | |
| + t :: change partition type ('fd' for Linux RAID auto) | |
| + w :: write changes and exit | |
| Of course in between steps you want to use *p* to print the | |
| partition table to check your work | |
| 3. Create RAID md devices | |
| _mdadm -C /dev/md0 -l raid0 -n 2 /dev/sd[b-c]1_ | |
| + -C or --create :: create md device | |
| + -l or --level :: RAID level (0,1,4,5,6,10) | |
| linear, stripe, mirror, raid4, raid5, raid6, raid10, | |
| multipath, faulty, container ... | |
| + -n or --raid-devices :: no. of RAID devices | |
| 4. Verify RAID device | |
| _cat /proc/mdstat_ | |
| - *Creating LVM partitions* (LFCS & LFS201 topic) | |
| 1. Create Physical Volume (PV) | |
| _pvcreate /dev/sdXY_ | |
| 2. Create Volume Group (VG) | |
| 3. Create Logical Volume (LV) | |
| 4. Make file system on LV | |
| _mkfs.ext[2,3,4,] /dev/VGname/LVname_ | |
| - *Configuring swap partitions* | |
| 1. _fdisk /dev/sdX_ | |
| n, p, 1, t, 82, w | |
| normally swap partitions are designated as type 82, but | |
| it is actually possible to use any partition type | |
| 2. _mkswap /dev/sdXY_ | |
| set up the linux swap area | |
| 3. _swapon /dev/sdXY_ | |
| enables the device for paging | |
| 4. edit /etc/fstab | |
| _/dev/sdXY none swap defaults 0 0_ | |
| - *File attributes* | |
| + lsattr :: list file attributes | |
| + a :: append only | |
| a file with 'a' attribute set can only be opened in | |
| append mode for writing | |
| + c :: compressed | |
| a file with 'c' attribute set is automatically compressed | |
| on disk by the kernel, but reads from the file return | |
| uncompressed data | |
| + d :: no dump | |
| if this attribute is set, the file will not be backed | |
| up when _dump_ is run | |
| + e :: extent format | |
| if this attrib is set, it means the file is using | |
| extents for mapping blocks on a disk | |
| + i :: immutable | |
| a file with this attrib set cannot be modified, deleted, | |
| renamed, and no link to the file can be created. This | |
| attrib *even prevents su from deleting or modifying* | |
| a file! | |
| + j :: data journalling | |
| if this attrib is set, all its data is written to the | |
| ext3 journal before being written to the file itself | |
| + s :: secure deletion | |
| if this attrib is set on a file, when the file is deleted | |
| all its block are zeroed and written back to the disk | |
| + t :: no tail-merging | |
| if this attrib is set on a file, a partial block fragment | |
| at the end of the file will _not_ be merged with other files | |
| + tail-merging :: efficiently use slack space at the end | |
| of large files by packing the 'tail'/last partial block | |
| of multiple files into a single bock | |
| + u :: undeletable | |
| if a file has this attrib set, when the file is deleted | |
| its contents are saved, allowing for the user to ask | |
| for its undeletion | |
| + A :: no atime updates | |
| if a file has this attrib set, when the file is accessed, | |
| its atime record is not modified | |
| + atime :: time a file was last accessed | |
| disabling this attribute can speed up file operations | |
| + C :: no copy on write | |
| if a file has this attrib set, a fs supporting CoW | |
| (Btrfs, for example) will not use CoW. CoW causes many | |
| small random writes for large files, so CoW should be | |
| disabled for DB files and VM images | |
| + D :: synchronous directory updates | |
| + S :: synchronous updates | |
| + T :: top of directory hierarchy | |
| + chattr :: change file attributes on Linux file systems | |
| part of the _e2fsprogs_ package | |
| + -R :: Recursively change attribs of dir's and their | |
| contents | |
| + -V :: verbose output | |
| + -f :: suppress error messages | |
| shut the *f*uck up | |
| + -v :: version | |
| + _chattr -R +C /MULTIMEDIA/VM_ | |
| disable CoW recursively in dir .../VM and its sub-dirs | |
| (+C means _no Copy-on-Write_) | |
| - *Filesystem checking* (LFS201 topic) | |
| + e2fsck :: check ext2,3,4 fs | |
| + fsck :: a wrapper for fs-specific fs-checkers | |
| - *Filesystem quotas and usage* (LFS201 topic) | |
| https://wiki.archlinux.org/index.php/Disk_quota | |
| + install disk package quota | |
| - quota-tools (Archlinux) | |
| - quota (RHEL and Ubuntu) | |
| + set up file system quotas | |
| + user quota (edit /etc/fstab) | |
| _/dev/sda1 /home ext4 defaults 1 1_ | |
| This is our fstab entry for 'home'. We will edit this to | |
| enable a user disk quota | |
| _/dev/sda1 /home ext4 defaults,usrquota 1 1_ | |
| + group quota (edit /etc/fstab) | |
| _/dev/sda1 /home ext4 defaults,usrquota,grpquota 1 1_ | |
| + create quota files in the fs | |
| _touch /home/aquota.user_ | |
| _touch /home/aquota.group_ | |
| + remount partitions with quotas | |
| _mount -vo remount /home_ | |
| + create quota index | |
| _quotacheck -vgum /home_ | |
| to create quota index for all partitions with quota | |
| mount options in /etc/mtab | |
| _quotacheck -vguma_ | |
| + finally, enable quotas | |
| _quotaon -av_ | |
| - Finding files on a filesystem | |
| + find | |
| + locate | |
| + ls | |
| - Formatting filesystems | |
| - ext2/3/4 filesystems | |
| - mkfs | |
| - XFS and btrfs filesystems | |
| - Mounting filesystems automatically at boot time | |
| you need to add an entry in /etc/fstab and make sure that the | |
| mountpoint exists | |
| - Mounting networked filesystems | |
| 1. NFS client config | |
| _mount -t nfs(nfs4) -o servername:/remoteDir /local/mntpt_ | |
| 2. Add NFS mount to /etc/fstab | |
| _server:/remote/export /local/mntpt nfsType options 0 0_ | |
| _servername:/music /local/music nfs4 rsize=8192,wsize=8192,timeo=14,_netdev 0 0_ | |
| + nfsTypes are _nfs_ (for nfs2,3) and _nfs4_ | |
| + rsize :: the number of bytes used when reading from the server | |
| + wsize :: the number of bytes used when writing to the server | |
| + timeo :: the amount of time, in tenths of a second, | |
| to wait before resending a transmission after an RPC timeout | |
| + _netdev :: wait until the network is up before | |
| trying to mount the share. systemd assumes this for NFS, | |
| but anyway it is good practice to use it for all types of | |
| networked file systems | |
| - Partitioning storage devices | |
| - Troubleshooting filesystem issues | |
| - *Linux Filesystem Tree Layout* (LFS201 topic) | |
| - Linux Filesystem Hierarchy | |
| + /bin | |
| + /sbin | |
| + /lib | |
| + /usr/bin | |
| + /usr/sbin | |
| + /usr/lib | |
| - *Linux Filesystems and the VFS* (LFS201 topic) | |
| - Virtual Filesystems | |
| + /proc | |
| + /sysfs | |
| - *Encrypting Disks with LUKS* (LFS201 topic) | |
| + create a LUKS partition | |
| 1. _cryptsetup luksFormat /dev/sdaX_ | |
| 2. _cryptsetup open --type luks /dev/sdaX LUKSname_ | |
| ** Local system administration | |
| - Creating backups | |
| t + tar cvf(z) | |
| - Restoring backed up data | |
| + tar xvf(z) | |
| - Creating local user groups | |
| + groupadd groupName | |
| - Managing user accounts | |
| + user management | |
| + cat /etc/group | |
| + usermod :: modify user account | |
| + -a :: add to group | |
| + -G :: used with -a | |
| + group management | |
| + groupmod :: modify group definition | |
| - Managing file permissions and ownership | |
| + chown :: change file or dir owner | |
| + -R :: recursively change ownership in dir and sub-dirs | |
| + chmod :: change rwx permissions | |
| - Managing fstab entries | |
| - Managing local user accounts | |
| - Managing the startup process and related services | |
| + chkconfig | |
| - Managing user account attributes | |
| + chmod | |
| - Managing user processes | |
| + top (or htop) | |
| + ps | |
| - Setting file permissions and ownership | |
| - *System startup and shutdown* (LFS201 topic) | |
| - init | |
| + systemV | |
| + upstart | |
| + systemd | |
| - bootloader | |
| + GRUB | |
| + GRUB2 | |
| - *Kernel Services and Configuration* (LFS201 topic) | |
| - *Kernel Modules* (LFS201 topic) | |
| + /proc/modules | |
| + lsmod | |
| - *Devices and udev* (LFS201 topic) | |
| + udevadm :: udev management tool | |
| - *Processes* (LFS201 topic) | |
| - *Signals* (LFS201 topic) | |
| - *System Monitoring* (LFS201 topic) | |
| - *Process Monitoring* (LFS201 topic) | |
| - *I/O monitoring and tuning* (LFS201 topic) | |
| + iotop | |
| + sar | |
| - *I/O Scheduling* (LFS201 topic) | |
| - *Memory: Monitoring Usage and Tuning* (LFS201 topic) | |
| + free | |
| + /proc/meminfo | |
| - *Pluggable Authentication Modules (PAM)* (LFS201 topic) | |
| - *Network Addresses* (LFS201 topic) | |
| + ip addr | |
| + ifconfig | |
| - *Network Devices and Configuration* (LFS201 topic) | |
| - *Basic Troubleshooting* (LFS201 topic) | |
| - *System Rescue* (LFS201 topic) | |
| - init 1, single-user mode | |
| - LiveCD boot, chroot | |
| ** Local Security | |
| - Accessing the root account | |
| - Using sudo to manage access to the root account | |
| + _visudo_ for editing /etc/sudoers | |
| + usermod -a -G wheel userName (RHEL, Arch) | |
| _usermod -a -G sudo userName_ (Ubuntu/Debian) | |
| - *Linux Security Modules* (LFS201 topic) | |
| + Ubuntu | |
| + apt-get install pkgname | |
| + apt-get update | |
| + apt-get dist-upgrade | |
| + apt-get remove pkgname | |
| ** Shell scripting | |
| - Basic Shell Scripting | |
| ** Software Management | |
| - Installing software packages | |
| + RPM | |
| + DPKG | |
| + yum | |
| + APT |
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