Linux is a Unix-like operating system, which can be used and distributed for free. It is a multi-user, multi-task, multi-thread and multi-CPU operating system based on POSIX and UNIX. It can run major UNIX tools, applications and network protocols. It supports 32-bit and 64-bit hardware. Linux inherits the network-centric design idea of Unix and is a multi-user network operating system with stable performance. Linux operating system was born in 199 1 year1year 10/0/0/5 (this is the first official announcement time). There are many different versions of Linux, but they all use the Linux kernel. Linux can be installed on various computer hardware devices, such as mobile phones, tablets, routers, video game consoles, desktop computers, mainframes and supercomputers. Strictly speaking, the word Linux itself only means Linux kernel, but in fact, people have become accustomed to using Linux to describe the entire operating system based on Linux kernel, and using GNU engineering tools and databases. Mbth Linux operating system was released in 199 1 year. Debian, RedHat and Slackware released by founder linus torvalds are free, reliable, safe, stable and multi-platform.
* * * There are four symbols representing standard input and output in Linux system. What do 0, 1 and 2 mean respectively?
The standard input is STDIN. In /dev/stdin, it generally refers to keyboard input. In the shell, the code is 0 standard output STDOUT, and in /dev/stdout, it generally refers to the terminal, that is, the display. In the shell, the code is 1 standard error STDERR, and in /dev/stderr, it also refers to the terminal. The difference is the error.
What is the representative of operating system based on graphical interface? Operating system?
Windows is the representative of graphic operating system. And osx and linux. Contrary to them, the non-graphical control system is now extinct, and the representative is dos.
What are the certifications of linux system?
Linux certification refers to the qualification obtained through examination after obtaining professional Linux training. At present, Linux certifications widely recognized in the world include LinuxProfessionalInstitute (LPI), SairLinux and GNU, Linux+ and RedhatCertificate engine.
Linux Vocational College (LPI)
As far as the Linux community is concerned, the LPI certification scheme has received the most extensive support. LPI has started the certification plan of institutionalized LinuXpression -Level 1 (LPIC- 1 for short) ahead of schedule, and will start the certification of Level 2 and Level 3 as scheduled in the near future. In order to get LPIC- 1 certificate, you must pass two 90-minute exams-101(lpgeneralinux, Part 1) and 102 (LPGENERALINUX, Part2). The candidates for LPI LPIC- 1 are mainly system administrators with at least 1 year working experience in Linux.
SairLinux and GNU
Like LPI, Sair provides three levels of certification programs;
level 1——SairLinuxGNUCertifiedAdministrator(LCA)
Level 2-SaillinuxgNucleifiedengineer (LCE)
Level 3-Chief Engineer (MLCE)
1 is a fully developed Sair certification project, which is the same as LPI.
Linux+
The Linux+ certification program initiated by CompTIA is the latest project to enter the Linux certification market. The program was officially launched on September 2, 20061,which attracted extensive attention from Linux practitioners and the industry. Almost all major certification publishing houses have written reference books for Linux+ certification, and many IT training centers are preparing Linux+ certification plans.
Like other certifications marked with "+"issued by CompTIA, the Linux+ qualification certificate can only be obtained by passing an examination (such examinations are held by VUE and Prometric Examination Centers). Once you get the Linux+ qualification certificate, the certificate is valid for life. The price of Linux+ exam is $65,438+090, and the exam takes the form of multiple-choice questions, and the exam time is 65,438+020 minutes. Many of the contents covered are exactly the same as those of Sair and LPI certification, but the difficulty is slightly reduced.
LPI and Sair certification programs are aimed at Linux network and system administrators with considerable experience, while Linux+ certification is mainly aimed at individuals who have only half a year of Linux experience and want to obtain basic Linux technical qualifications.
RedHatCertifiedEngineer
Linux+ represents the low-level Linux authentication scheme, while the advanced Linux authentication scheme has been almost completely dominated by RHCE (RHCE) authentication scheme for a long time. RHCE is the most challenging certification test in this field, so it is also the most valuable Linux certification. But it is also the most expensive. The cost of the whole course is $2,498, or you can take the certification exam alone for $749.