While in some ways similar to an editor which permits scripted edits (such as ed), sed works by making only one pass over the input(s), and is consequently more efficient. Sed is a stream editor. But it is sed’s ability to filter text in a pipeline which particularly distinguishes it from other types of editors. A stream editor is used to perform basic text transformations on an input stream (a file, or input from a pipeline).
From a terminal, switch to root and do the following: [[email protected]]$ su Password: [[email protected]]# cp /etc/inittab /etc/ inittab. You want to make runlevel 3 your default runlevel. Bak #Make a backup copy of /etc/inittab [[email protected]]# sed -i 's/id:5: initdefault:/id:3:initdefault:/' /etc/inittab #Make runlevel 3 your default .
On Oracle Enterprise Linux 5. One of the significant benefits of MySQL is it’s ease of use. Generally already installed on most Linux systems, MySQL can be installed by a single command if not yet present. 4 you can use the following commands to check for MySQL, configure your yum repository and install MySQL.
For example, if you were to query your data on external_id, without an index the system will need to read all data pages and then sequential scan pages to identify matching records. As there is no information known about how many rows satisfy the criteria, all data must be read. You can confirm this with the QEP. Quite simply, you have an index on a single column to help with performance.
The introduction of Lua into Sysbench may now be a better option then my tool of choice mybench which I use simply because I can configure, write and deploy generally for a client in under 1 hour. Of course, the data is only the starting point, having representative transactions and queries to execute and a framework to execute and a reporting module are also necessary.
Recently however I was able to work with a client, first in resolving critical performance issues and then in a review of the application architecture and MySQL environment, provide recommendations and also helping internal resources in the successful implementation. The result was a very successful engagement and an ideal case study on a strategy for tackling improving performance of an application using MySQL.
The s command is probably the most important in sed and has a lot of different options. Its basic concept is simple: the s command attempts to match the pattern space against the supplied regexp; if the match is successful, then that portion of the pattern space which was matched is replaced with replacement.
Si tu utilises GNU/sed, tu peux utiliser l’option -i pour te faciliter la vie. Ton premier exemple se transforme en : sed -i -e “s/chaines1/chaine2/g” fichier.
Документация по Red Hat Enterprise Linux на русском языке. Руководство пользователя и администратора RedHat.
Knowing how to view certain sections, how to replace words, and how to filter content from those files are skills you need to have handy without having to do a Google search. Every system administrator has to deal with plain text files on a daily basis.
Commands within a script or script-file can be separated by semicolons (“;”) or newlines (ASCII code 10). Commands can also be preceded with optional non-significant whitespace characters. Some commands, due to their syntax, cannot be followed by semicolons working as command separators and thus should be terminated with newlines or be placed at the end of a script or script-file.