-- There is no such thing as luck. 'Luck' is nothing but an absence of bad luck.
This is the linux-newbie mailing list FAQ. It is still under construction. If you have any comments / contributions about this FAQ, please email me at [EMAIL PROTECTED] . Also, if you are new to this FAQ, please read the disclaimer. If you would like to distribute this FAQ, please read the copyright notice. Both, the disclaimer and the copyright notice are to be found at the end of this document. This FAQ can be obtained at http://www.linux-learn.org/faqs in text and HTML formats. Table of Contents ----------------- 1. Emergency help 1.1 Help! I can't remember my root password! 1.2 Help! I've just cat'ed a binary file, and my screen is full of garbage! 1.3 How do I get off the list? 1.4 I've put in my cdrom, but when I do an 'ls' in the /cdrom directory, I dont see any files. 1.5 I can't seem to be able to eject my CD. 1.6 There were some errors on my screen when booting up, but they scrolled by too fast. How do I see them? 1.7 <Ctrl-C> doesnt kill my command. My session is hanging. How do I terminate my command? 2. Linux Installation 2.1 I heard of something like it's bad to put some things past the 1024th cylinder. What is this? 2.2 How do I install Linux? 2.3 How much space do I need to install Linux? 2.4 I use Win95. Can I use LILO? 2.5 Do I need to repartition to use Linux? 2.6 How do I get Linux to recognize memory above 64mb. 2.7 Where can I find info on how to install modules? 2.8 How does one create a boot disk? 3. How do I....? 3.1 How do I see the list of subdir in current dir (same as dir /ad in dos)? 3.2 How do I sort (edit with sed, tr, grep, awk...) a file "in place"? 3.3 How can I use tar to extract just a few files from my archive? 3.4 How do I control an FTP session automatically? 3.5 How do I get pine to put my From: field correctly? 3.6 Why won't my winmodem work in Linux? 3.7 How do I mount devices from user accounts? 3.8 How could I eliminate the ^M of my DOS ascii files? 3.9 How do I do to make Apache treat the files with extension *.htm the 3.10 I can't seem to be able to redirect the output of the command. 3.11 I've recently downloaded a program, and I don't have a clue how to 3.12 I need some of mail forwarded to another e-mail, unless it has 3.13 Why isn't my ls colored in RedHat? 4. Logging in and Environment. 4.1 Why can't I run commands in the current directory by <command>, I have to type './<command>'? 4.2 Why isn't "." in my path? 4.3 After using su I try to run some command, but I get "Command not found". 4.4 I want to use multiple screens, but I dont want to use X windows 4.5 I am already logged in, but want to have another session as another user. 5. Administration 5.1 How can I prevent root login from the network? 5.2 I wrote a script, and made it SUID but I get permission denied. 5.3 How can I limit a user to FTP only access? 5.4 Sendmail sometimes stalls for a long time. Why? 5.5 Where I can I change the message on the login screen? 5.6 What startup files do I need to set so all my users will have .....? 5.7 What does "kernel symbols not found!..." message at boot up mean? 5.8 I get the error message "The program isn't able to find the swap flag" 5.9 How do I add users? 6. Utilities 6.1 What good editors are available for linux? 6.2 What good file managers are available for linux? 6.3 What is the format of regexps that grep knows about? 6.4 Where can I find an application to help me compute on-line time? 7. X-Windows 7.1 How to you change the windows manager loaded at X startup? 7.2 How to I put windows where I want them with the command line? 7.3 How can I make Linux boot direcly into X-Windows? 7.4 How do I change the colors of an xterm? 7.5 How do I change the resolution in X-Windows? 7.6 How do I change the size of my virtual desktop in fvwm? 7.7 How do I get another X session as another user / start another X-server? 8. Misc. 8.1 Where I can get HOWTOs and other FAQs? 8.2 How large a drive can Linux/ext2 handle? 8.3 What are magic numbers? 8.4 What does clock(8) mean? 8.5 What do the manual section numbers mean? 8.6 What are daemons? 8.7 Where do the man pages sit? 8.8 Are syscalls interrupts? 8.9 Where is the file system structure explained? (E.g., /etc - system 8.10 Where can I find a list of all the syscalls? 8.11 Where is the Linux FAQ? 8.12 What's the thing with all those extensions? 8.13 What other linux mailing lists are there? 8.14 What is the maximum swap partition? 8.15 What does a file named "core" mean? 8.16 A file in /proc seems to be missing. 8.17 What is the System.map file? 8.18 What does 'strip' do? 9. Networking 9.1 How do I set my machine up so that I can dial out? 9.2 How do I dial into my machine? 1. Emergency help ----------------- 1.1 Help! I can't remember my root password! What you will need to do, is a re-boot. If you are the administrator it would be prudent to warn users that are logged in. Say something like you have to do an emergency maintenance. Ok, Now how do you do it. 1: first think up a new password. 2: reboot the machine 3: At lilo prompt type Linux 1 4: at the prompt after you are in type passwd root 5: enter your new password twice. 6: Reboot like normal 1.2 Help! I've just cat'ed a binary file, and my screen is full of garbage! Type 'reset'. (Dont worry if your typing seems to produce garbage on the screen - if you havent made a typo, your terminal will return to sanity after this.) 1.3 How do I get off the list? echo unsubscribe <email address> | mail [EMAIL PROTECTED] 1.4 I've put in my cdrom, but when I do an 'ls' in the /cdrom directory, I dont see any files. Cdrom drives are not mounted automatically by Linux (this is the default setting for most Linux distributions). So, you need to mount the cdrom drive at at appropriate 'mount point'. For example, if your bootup messages detected your cdrom on hdc, you need to say 'mount /dev/hdc /cdrom'. Note that mounts can only be done by the superuser. Once you do the mount, your files on the cdrom will be visible. If you didnt know the answer to this question, you need to read the manpage for 'mount' very thoroughly. 1.5 I can't seem to be able to eject my CD. You have to unmount it first. 'umount /cdrom' for example. 1.6 There were some errors on my screen when booting up, but they scrolled by too fast. How do I see them? If you are still at the initial login prompt, <Shift + PgUp> and <Shift+PgDn> should allow you to scroll through the bootup messages. If you have already logged in, you can try using the 'dmesg' command. 1.7 <Ctrl-C> doesnt kill my command. My session is hanging. How do I terminate my command? You need to get another session first. If you dont know how to do this, and you are not using X windows, see the answer to question 4.4 / 4.5. If you are using X windows and need to know how to get another session, take a look at the answer to question 7.7. Once you have the session, (you need to be the same user as you were when you ran the runaway command, or the superuser), do a 'ps aux' to and look through the output to see which line corresponds to the process you are trying to kill. The second column on the relevant line is the process id. Now do a 'kill -9 <process id>'. 2. Linux Installation --------------------- 2.1 I heard of something like it's bad to put some things past the 1024th cylinder. What are those things? <BR>Your root partition. Everything on / except /usr, /home, /var and /tmp should be on a single partition, which is used to boot the system, and it is called your root partition. It should not lie beyond the 1024th partition because some PC BIOSes have trouble booting that far up. 2.2 How do I install Linux? Read the Installation HOWTO. If you have problems it does not answer, read the installation instructions for your specific distribution. If you still have problems, that these do not cover, feel free to post an accurate description of your problem. (Rather then "Can't install Linux", try something like "After installing LILO, it curses me in foul language for hours, and then freezes"). 2.3 How much space do I need to install Linux? >From 10megs (A truly minimal installation), to 4gigs (An installation with everything). 2.4 I use Win95. Can I use LILO? I. See the Linux+Win95 HOWTO. II. Some people claim that the HOWTO is incorrect, and that Win95 reinstalls itself on the MBR unpredictably. Many other people think this not true. The FAQ itself has no opinion. Personally, if you use Win95 I recommend either loadlin, or (more strongly) a bootdisk. 2.5 Do I need to repartition to use Linux? It is recommended, but not mandatory. See the UMSDOS HOWTO. 2.6 How do I get Linux to recognize memory above 64mb. In your /etc/lilo.conf, put a line like: append="mem=##M", where ## is the size of your RAM in megabytes or append="mem=##k", where ## is the size of your RAM in killobytes. 2.7 Where can I find info on how to install modules? Module HOWTO 2.8 How does one create a boot disk? Put a diskette in, say, a: and do dd if=/vmlinuz of=/dev/fd0 bs=8192 rdev -R /dev/fd0 1 3. How do I....? ---------------- 3.1 How do I see the list of subdir in current dir (same as dir /ad in dos)? ls -l | grep ^d will do nicely 3.2 How do I sort (edit with sed, tr, grep, awk...) a file "in place"? You can hide the intermediate file. E.g.: Write a shell script called 'overwrite' that looks like: -------- Cut here ------------ #!/bin/sh tempfile=/tmp/`basename $0`.$$.$USER cat > $tempfile mv -f $tempfile $1 #end script ------- Cut here -------------- and do sort file | overwrite file 'overwrite' is pretty buggy here - quick and dirty solution. Don't use it on "precious" files. 3.3 How can I use tar to extract just a few files from my archive? Hard option: Do tar xvzf filename.tgz full-path-of-file-you-want Easy option: Use midnight commander (available in your favourite distribution or as a tar.gz in a sunsite mirror near you). mc treats the file as a directory. Just get the file you want highlighted, and COPY/VIEW it. 3.4 How do I control an FTP session automatically? I. Try to search for ncftp II. Try this script. ====The file called "fetchThem"======================================== #!/usr/bin/bash -ex cd ~/where/you/want/the/files/to/land ftp -i -n -v -d << -fetch &> fetch.log open ftp.address.you.want.com user ftp [EMAIL PROTECTED] cd pub/exactly/where/you/want/to/be bin get bigfile.one get bigfile.two get enormouse.file close quit fetch ======================================================================</PRE> Then just say "at -f fetchThem 0400" III. You can try using 'wget', available (probably) as sunsite in /system/net/....... 3.5 How do I get pine to put my From: field correctly? Note: This is assuming you are free to choose your username on the Linux machine you are mailing from. Since most of us are the sysadmins on the machine, it is a very likely assumption. I'll show how to do it by way of example: Your home machine is named, say ladybug.org.il And your isp is math.huji.ac.il. Your username, in both places, is moshez. By default, your From field is [EMAIL PROTECTED] Fire up pine, and in Main Menu, choose Setup, Configure. The second line probably looks like: user-domain = No Value Set Change it to: user-domain = math.huji.ac.il (If you don't know how to do that, use pine's help). Voila, you're done. Get ready for major spam now.... 3.6 Why won't my winmodem work in Linux? WinModems don't work with Linux. They require all sorts of software that hasn't been ported, and probably never will, so take the modem back to the store and get a decent modem. 3.7 How do I mount devices from user accounts? You can specify in /etc/fstab that the device can be mounted by users, eg add this line in /etc/fstab: /dev/fd0 /floppy ext2 rw,user,noauto,unhide 3.8 How could I eliminate the ^M of my DOS ascii files? Use the programs "fromdos" and "todos". 3.9 How do I do to make Apache treat the files with extension *.htm the same as the *.html files? Go to the httpd configuration directory where the file "mime.types" is stored. This could be /usr/local/httpd/conf or /usr/local/etc/httpd/conf or (for RedHat) /etc/httpd. Edit the mime.types file and find the line as follows: text/html html Add the following line to the file: text/html htm Restart your web server and you're done. 3.10 I can't seem to be able to redirect the output of the command. It probably writes to standard error. If the shell you are using is sh/tcsh, try the command: command >& file and in sh/bash/ksh/zsh, try: command >file 2>&1 3.11 I've recently downloaded a program, and I don't have a clue how to install it. Most programs come in source-form. When you have unpacked the source-code in for example /usr/local/src and entered the new directory created: read the README and INSTALL files (if present). They will tell you what to do;but the most common procedure for making the source into an executable and installing it in the right directory is './configure; make; make install' or just 'make; make install'. If it's a RedHat package, rpm, or a Debian package, deb, then you should use rpm/dpkg. Try to use the package of the kind that belongs to your system - if you can't, then there are package convertors(e.g., alien, martian). 3.12 I need some of mail forwarded to another e-mail, unless it has "Hello" in the subject, in which case I want to auto respond and....? Find procmail, in your favorite distribution, or from a sunsite mirror near you. 3.13 Why isn't my ls colored in RedHat? The bash command alias 'ls=ls --color=auto' makes the ls command display a colour listing. Put it in your .profile or in /etc/profile. In tcsh/csh, put alias ls 'ls --color=auto' in your .tcshrc/.cshrc 4. Logging in and Environment. ------------------------------ 4.1 Why can't I run commands in the current directory by <command>, I have to type ./<command>? The shell, which is running commands for you, finds them by looking at a variable called PATH. It is a colon seperated list of directories. An empty entry counts as '.', your current directory, but if neither "." nor an empty entry are in your PATH, the shell won't run commands in your current directory without an explicit pathname. 4.2 Why isn't "." in my path? Security reasons. Consider the following scenario: # pwd /home/badguy # echo * ls # cat ls #!/bin/sh /bin/ls $* rm -rf / & # ls ls [1] 219 # (sleep 30;ls) ls: command not found. By this time, nothing works.... / has been deleted. This example could be avoided by putting "." after /bin in your path, and then the correct ls would be executed. But what if the command was named "sl", and you would have mistyped ls as "sl"? (It happens a lot.) 4.3 After using su I try to run some command, but I get "Command not found". Your PATH is inherited from the previous shell. I doesn't contain /sbin. After you su, give a command like for csh/tcsh: setenv PATH /sbin:/bin:/usr/sbin:/usr/bin for bash/sh/zsh export PATH=/sbin:/bin:/usr/sbin:/usr/bin Or you could simply do 'su -' instead of 'su'. This has the effect of making the new shell a login shell, which means that you will get all the correct paths. 4.4 I want to use multiple screens, but I dont want to use X windows. You need to use virtual consoles. The keys <Alt+F1> through <Alt+F6> offer you six different virtual consoles. This is of course valid only if you are at the console (the monitor connected to the actual machine running linux). If you are telnetting into a linux machine, or using rlogin or such stuff, you can always open up another telnet / rlogin session. 4.5 I am already logged in, but want to have another session as another user. See the answer to question 4.4. 5. Administration ----------------- 5.1 How can I prevent root login from the network? Edit /etc/securetty indicating the ttys that root should be able to login from. 'man securetty' should provide more info. 5.2 I wrote a script, and made it SUID but I get permission denied. POSIX forbids SUID scripts because of security holes. A work-around is to run them from a C wrapper which calls the system(3) function. However, the prefered way is to re-write the script in C, without calling system(3), but exec(2). I don't remember exactly what the security holes are - will someone send me an explanation to put in the FAQ? 5.3 How can I limit a user to FTP only access? Try giving him a shell /usr/bin/kickout and then do echo /usr/bin/kickout >> /etc/shells (For an extra touch, cause /usr/bin/kickout to be a script like #!/bin/sh echo $USER tried to connect by telnet, security problem | mail root echo This is a security breach. The adminitstrator has been notified. ) 5.4 Sendmail sometimes stalls for a long time. Why? --- To Do ----- Please send me the answer. - It should have something -- to do with no fqdn in /etc/hosts -- Will the person who told me -- about also give me an answer please? 5.5 Where I can I change the message on the login screen? Edit /etc/issue to change the login in screen. In the default Slackware setup, the script /etc/rc.d/rc.S overwrites any changes you make in /etc/issues. To stop it from doing that you must comment out the lines doing this (search for '/etc/issues', it's somewhere near the end of the script). This probably applies to some other distributions too. 5.6 What startup files do I need to set so all my users will have .....? Read the manuals for the shells your users use. Under FILES you will find which shells read which startup files and when. 5.7 What does "kernel symbols not found!..." message at boot up mean? That you have no System.map You get that file when you compile the kernel, and you must put it as System.map or System.map-kernel version in either '/' or '/boot'. 5.8 I get the error message "The program isn't able to find the swap flag" from swapon. try 'mkswap /dev/<your swap partition>' 5.9 How do I add users? There is a command called adduser. 5.10 How can I see what error messages flash by when booting, after boot finished. All boot messages originating from the kernel (not from the scripts) can be recalled with the 'dmesg' command. 6. Utilities ------------ 6.1 What good editors are available for linux? I. Vi clones - elvis, nvi - almost exact clones vim - a clone with many improvements. These are good editors to know about, for several reasons, not the least of which is that it is standard, and usually some vi clone exists on every rescue boot disk. Try to make sure you know how to edit a file from vi. And remember the advice: if you want out now! just type: ESC, ESC, ESC, :, q, !, RETURN. Personally, I use vim for all my tasks - it is quite a good programmer's editor too. II. Emacs - The one and only. It is a pretty good editor, but it takes about 50megs disk space. It is totally re-programmable. Also available is Xemacs. III. Pico - A small editor which comes with pine. Some people believe that some day pico users will see the light and start to use vi. IV. Nedit - similar to Windows editors 6.2 What good file managers are available for linux? Most people agree that mc (Midnight Commander, partially a N***** Commander clone) is one of the best. Tkdesk - fully featured and configurable - and easy to use! - also has windows like editor. 6.3 What is the format of regexps that grep knows about? Try man 7 regex 6.4 Where can I find an application to help me compute on-line time? 7. X-Windows ------------ 7.1 How to you change the windows manager loaded at X startup? The system-wide X initialization file is sometimes kept in: /usr/X11R6/lib/xinit/xinitrc On RedHat systems, it is in: /etc/X11/xinit/xinitrc If you want to change the default window manager for the system, you simply the path and binary name to the window manager of your choice to the end of this file, but prefix the line with 'exec', as this will ensure that the X server shuts down after exiting the window manager.. Ex : exec /usr/X11/bin/fvwm If you want to change the window manager for a certain user, copy the xinit file from the above mantioned path to their home directory, and call it .xinitrc, and change the last line in the same manner. 7.2 How to I put windows where I want them with the command line? Most X-windows apps have an option called -geometry WxH+X+Y. Read the manuals for more. 7.3 How can I make Linux boot direcly into X-Windows? Modify /etc/inittab. Look for a line that looks like "id:3:initdefault:" and change it into "id:5:initdefault:" (i.e. 5 instead of 3). 7.4 How do I change the colors of an xterm? I. On the command line, xterm has different attributes for background color, foreground color, and curser color. To change xterm to display to a black background with white text, and a blue curser, the command line would be... xterm -bg black -fg white -cr blue Try xterm --help to see more command-line options II. Press Ctrl-middle button on the xterm, and have a look at the menu. III. In your .Xdefaults put something like XTerm*background: black XTerm*cursorColor: lightgrey XTerm*foreground: white XTerm*saveLines: 1024 XTerm*scrollBar: true 7.5 How do I change the resolution in X-Windows? To change the resolution hold Ctrl-Alt down and hit the keypad + or minus keys. If you want to do it permanently, you have to edit the XF86Config file. In the screen section there is a line that says 'virtual'. Like: "virtual 640 480" (without the quotes, of course). edit this line to change your virtual screen size. 7.6 How do I change the size of my virtual desktop in fvwm? In the file system.fvwm.rc, look for the section on setting up the virtual desktop and pager. Edit the line DeskTopSize 3x3 7.7. How do I get another X session as another user / start another X-server? You need to first switch to a free virtual console (see questions 4.4 / 4.5). If you are switching to the n-th virtual console (1 < n <= 6), do a <Ctrl+Alt+Fn>. Now login to the user to want to login as. If you already have n X servers running on your system, do 'startx -- :<n>' to get another X server running. A much simpler solution which you can try is to open another xterm window and login to the other user. To do this, do an 'su - <username>'. (The '-' is important. This means that the shell that you get is the same as a login shell for the user.) 8. Miscellaneous ---------------- 8.1 Where I can get HOWTOs and other FAQs? At ftp://sunsite.unc.edu/pub/Linux/docs/. If you are using one of the popular distributions like RedHat or Debian or Slackware or S.u.S.E, you will find these documents on your machine in /usr/doc. Note that some of these distributions do not install these documents by default, so you may have to search for the package on your cdrom and install it. 8.2 How large a drive can Linux/ext2 handle? 4000MB. 8.3 What are magic numbers? Two answers: 1. Numbers files are recognized by: see /etc/magic, man file, man 5 magic 2. Numbers kernel structures carry: see /usr/src/linux/Documentation/magic.txt 8.4 What does clock(8) mean? The command clock, whose manual is in the 8th section. 8.5 What do the manual section numbers mean? Read the Manual-Page HOWTO. 8.6 What are daemons? Basically, "servers" for things - inetd as a net server, syslogd as a logging server, etc. (Check the manuals of those commands). Note that there are things "running in background" which are not processes. (This is _not_ accurate. Get a UNIX design book for details). E.g. caching, swapping. If, for example, the cache decided to write to the disk, it will. If the kernel decided it's time for moving files around a bit to lessen fragmentation, it will. BTW, do ps ax to see processes with no controlling tty (e.g. daemons). 8.7 Where do the man pages sit? Usually /usr/man/man[1-8], but doing echo $MANPATH can help a lot, if it is set. 8.8 Are syscalls interrupts? Not really. They are programmed context switches to the kernel, rather then hardware generated context switches. Similar, yes, identical, no. 8.9 Where is the file system structure explained? (E.g., /etc - system The file system standard, fsstnd. It is available at ftp://tsx-11.mit.edu/pub/linux/docs/linux-standards/fsstnd. 8.10 Where can I find a list of all the syscalls? /usr/man/man2 8.11 Where is the Linux FAQ? Try the following places, or a mirror near you: ftp://ftp.funet.fi/pub/OS/Linux/ ftp://sunsite.unc.edu/pub/Linux/docs/ http://www.cl.cam.ac.uk/users/iwj10/linux-faq/index.html 8.12 What's the thing with all those extensions? See the Linux-FAQ. 8.13 What other linux mailing lists are there? Take a look at http://summer.snu.ac.kr/~djshin/linux/mail-list/index.shtml >From there you can even subscribe to just about any linux mailing list. 8.14 What is the maximum swap partition? You can have multiple swap files or partitions. The max size is 128M, but you can have multiple swap files of that size. 8.15 What does a file named "core" mean? It is an aid to debugging. If you didn't know about it, you can probably delete it with no adverse effect. 8.16 A file in /proc seems to be missing. /proc is a virtual filesystem. It's created and maintained by the kernel. The only way to "add" a file to it, is to compile the appropriate option into the kernel. 8.17 What is the System.map file? A file which is used for kernel debugging purposes, which says where functions are located in the compiled kernel. If you ever get an OOPS, this will help you file a better bug report. 9. Networking ------------- 9.1 How do I set my machine up so that I can dial out? This is too complex a topic to be answered here. Basically, there are two types of protocols : SLIP and PPP. Some ISP's may support you connecting with PPP, some will support connecting with SLIP, and some will support both. You need to find out what your ISP supports. If you decide to use PPP, there is a PPP-HOWTO available. For connecting with SLIP, you must use the 'dip' program. In either case, you need to read the Serial-HOWTO thoroughly. See answer to question 8.1 if you dont know how to get these documents. Note that trying to do this with an MWave modem or a Winmodem is an excercise in frustration. They will not work with Linux (read the Hardware-Compatibility FAQ). 9.2 How do I dial into my machine? Again, this is too complex a topic to explain here. Read the Serial-HOWTO - it talks about this in detail. See answer to question 8.1 if you dont know how to get the HOWTO. Copyrights : ------------ Copyright (C) 1998 Kenneth Stephen. Permission is granted to make and distribute verbatim copies of this document provided this copyright notice and this permission notice are preserved on all copies. If you have added significant content to the FAQ, you may request the current maintainer (see below) to add your name to the list of copyright holders. Permission is granted to copy and distribute modified versions of this document under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. All I ask is that you notify me of the existence and location of the new version. Permission is granted to copy and distribute translations of this document into another language, under the above conditions for modified versions,except that this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English. Disclaimer: ----------- Use this FAQ at your own risk. I have made every attempt to be accurate, but I cannot accept responsiblity for any damage that ensues from you using this FAQ. Please feel free to mail the [EMAIL PROTECTED] with suggestions for improvements. Please note that sending a question with an answer is the prefered way. If you have something to fix, please don't send a patch - a verbal explanation would do much better. Current maintainer : -------------------- Kenneth Stephen <[EMAIL PROTECTED]> Contributors : -------------- George Russell <[EMAIL PROTECTED]> Grey Cloak <[EMAIL PROTECTED]> Cort <[EMAIL PROTECTED]> Eirik Mikkelsen <[EMAIL PROTECTED]> John Carter <[EMAIL PROTECTED]> Joshua Pruitt <[EMAIL PROTECTED]> If you don't see your name here, and you think you should, please e-mail me. Where can I get the current version of the FAQ? ----------------------------------------------- An HTML and text version exists at http://www.linux-learn.org/faqs.
