How to grep a file?

How to grep all files in a dir?

How to list files that contain a particular string? (grep -l)

“Alt+x grep-find”.

The grep-find command will invoke find . -type f -exec grep -nH -e MySearchStr {} /dev/null \; or grep -r <C> -nH -e . –include=, depending on which distro or version of emacs. Emacs will promp the above command in the minibuffer, then you can edit it to modify your search word, or type name extension to search. When you execute the command, emacs will place the output in a formated and linked way in another pane.

If you use the command often, you can creat a alias or keyboard shortcut. Here’s the code to put in your emacs init file:

Xah Lee, 2006-06, 2009-08, 2009-09-29

Suppose you need to do find and replace of a string pattern, for the hundreds of files in a directory. However, you do not want to replace all of them. You need to look at it in a case-by-case basis. What can you do?

Answer: emacs.

Solution

• Call “dired” or “find-dired” to list files in dir and all subdirs.
• Mark the files you want. You can mark by regex by typing “%m”
• Type “Q” to call dired-do-query-replace-regexp.
• Type your find regex and replace string.
• For each occurance, type “y” to replace, “n” to skip, “!” for replacing all occurances in current file. Type “Ctrl+g” to abort the whole operation.
• To do the replacement on all files without further asking, type “Y”. To skip all possible replacement on the rest of the current file, type “N”. (These are Emacs 23 only)
• Call “ibuffer” to list all opened files.
• Type “*u” to mark all unsaved files, type “S” to save all marked files, type “D” to close them all.

Step-by-Step Guide

Select Target Files

Start emacs by typing “emacs” in the command line interface prompt. (Or, double click the Emacs icon if you are in a Graphics User Interface environment)

Selecting Files In A Directory

First you need to select the files you want to do the replace. Use the graphical menu “File‣Open Directory”. Emacs will ask you for a directory path. Type the directory path, then press Enter.

Now, you will be shown the list of files, and now you need to “mark” the files you want the regex find-replace to work on. You mark a file by moving the cursor to the file you want, then press “m”. Unmark it by pressing “u”. (To list subdirectories, move your cursor to the directory and press “i”. The subdirectory’s content will be listed at the bottom.) To mark all files by a regex, type “%m”, then type your regex pattern. For example, if you want to mark all html files, then type “%mhtml$”. (You can find a list of the mark commands in the graphical menu “Mark” (this menu appears when you are in the dired mode).)

Selecting Files In A Directory And All Its Subdirectories

If you want to do find and replace on files inside a directory, including hundreds of subdirectories, here’s a method to select all these files.

Press the “Esc” key, then press the x key, then type “find-dired”. (then press Enter) Then, type a directory name, e.g. “/Users/mary/myfiles”

Emacs will ask you with the prompt “Run find (with args): ”. If you need to do the replacement on all html files, then type “-name “*html””. If you don’t care about what kind of file but simply all files under that dir, then give “-type f”.

Now, mark the files as described above.

Interactive Find & Replace

Now, you are ready to do the interactive find replace. For simplicity, let’s say you just want to replace the word “quick” by “super”. Now, type “Esc x dired-do-query-replace-regexp”. It will prompt you for the regex string and the replacement string. Type “quick”, enter, then “super”.

Now, emacs will use your pattern and check the files, and stop and show you whenever a match occurred. When this happens, emacs will prompt you, and you have a choice of making the change or skip the change. To make the change, type “y”. To skip, type “n”. If you simply want emacs to go ahead and make all such changes to the current file, type “!”.

If you want to cancel the whole operation without saving any changes you’ve made, type “Ctrl+g”, then exit emacs using the menu “File‣Exit Emacs”.

Saving the Changed Files

Now, after you went through the above ordeal. There is one more step you need to do, and that is saving the changed files.

If you have emacs version 22, you can type “Esc x ibuffer” to go into a buffer listing mode, then type “*u” to mark all unsaved files, then type “S” to save them all. (that’s shift-s)

If you are using a emacs version 21, then you can do this: type “Esc x list-buffer”, then move the cursor to the file you want to save and type “s”. It will mark the file for later save action. Type “u” to unmark. Once you are done, type “x” to execute the saving of all files marked for save. (in emacs, opened file is called “buffer”. Disregard other things there.)

Alternative to the above options, you can also type “Esc x save-some-buffers”. Then emacs will display each unsaved file and ask if you want it saved.

Converting Numbers to Binary, Octal, Hexadecimal forms.

To convert the decimal 10 to binary representation in calc, type “10 Enter d2”. The d2 will display all numbers in the window in the binary form. The numbers will have a “2#” prefix to indicate that they are in base 2. To display them back in decimal form, type “d0”. To show numbers in octal or hexadecimal form, type “d8” or “d6”.

To convert a binary number 1010 to decimal, type “2#1010 Enter” to enter the number then type “d0” to show all numbers in decimal form. Similarly, to enter a number in octal form, precede it with “8#” and hexadecimal numbers are prefixed with “16#”.

unit conversion

To find out what is 40 F° in C°, type “40 Enter ut dF Enter dC Enter”.

Is there a way for emacs to interpret the file as hex-decimal? (i.e. byte-code editor)

To open the file as hex, call hexl-find-file. If the file is already opened, call hexl-mode.

How to set the background color so that all new “frames” will have that color? (not set-background-color)

“Alt+x customize-variable Enter default-frame-alist Enter”

If you want to code elisp manually, see Ctrl+h v default-frame-alist. Here’s a example you can put in your emacs init file:

To see a list of color names emacs support, call list-colors-display.

Alias Long Commands to Shorter Names

Many emacs’s commands have long names. You can alias frequently used commandsto shorter names.

For example, here is some of my aliases:

The default keyboard shortcut for execute-extended-command is “Alt+x”. You can define “Alt+a”, which makes it on the home row. (See A Ergonomic Keyboard Shortcut Layout For Emacs)

Use this code:

How to set emacs so that all backups are directed into one folder? (such as at a directory “~/myBackups”)

Use the following lisp code in init file:

The above will mirror all directories at the given backup dir. For example, if you are editing a file “/Users/jane/web/xyz/myfile.txt”, and your backup root is “/Users/jane/.emacs.d/emacs-backup”, then the backup will be at “/Users/jane/.emacs.d/emacs-backup/Users/jane/web/xyz/myfile.txt~”.

If you want all backup to be flat in a dir, use the following:

This will create backup files flat in the given dir, and the backup file names will have “!” characters in place of the directory separator. For example, if you are editing a file at “/Users/jane/web/xyz/myfile.txt”, and your backup dir is set at “/Users/jane/.emacs.d/emacs-backup”, then the backup file will be at: “/Users/jane/.emacs.d/emacs-backup/Users!jane!web!emacs!myfile.txt~”. If you use long file names or many nested dirs, this scheme will reach file name length limit quickly.

How to record a sequence of keystrokes?

To record keystrokes, type “Ctrl+x (” then start typing your keystrokes. When done, type “Ctrl+x )”. This records your keystrokes. To run the keystrokes you’ve recorded, type “Ctrl+x e”.

Here are the command names and their shortcuts:

If you want to use your keyboard macro for future use, you can save it. To save the macro, first type “Alt+x name-last-kbd-macro”, then type “Alt+x insert-kbd-macro”, which will insert the lisp code for the keyboard macro at the cursor point. Put the code in your emacs init file (usually at “~/.emacs”). Then, you can execute your keyboard macro like this: “Alt+x yourMacroName” the next time you start emacs.

How to replace unprintable characters such as tabs or line return chars in Emacs?

Use any of the find/replace commands (Example: Alt+x query-replace) as usual, type the unprintable char by preceding it with “Ctrl+q”. Example: type “Alt+% Ctrl+q Ctrl+j Enter Space Enter”, will replace all returns with spaces.

The “Ctrl+q” does the command quoted-insert, which will let you enter the next charater literally. For example, to type a literal tab, press “Ctrl+q” then the Tab key. Some characters do not have a representation on the keyboard (for example, unix’s line return the form feed), so emacs provides the “Ctrl+j” method to input them. Here’s a short table on how to enter common unprintable chars:

If you are confused by all these notations, see this article The Confusion of Emacs’s Keystroke Representation for a explanation.

How to replace unprintable characters such as tabs or line return chars in Emacs?

Use any of the find/replace commands (Example: Alt+x query-replace) as usual, type the unprintable char by preceding it with “Ctrl+q”. Example: type “Alt+% Ctrl+q Ctrl+j Enter Space Enter”, will replace all returns with spaces.

The “Ctrl+q” does the command quoted-insert, which will let you enter the next charater literally. For example, to type a literal tab, press “Ctrl+q” then the Tab key. Some characters do not have a representation on the keyboard (for example, unix’s line return the form feed), so emacs provides the “Ctrl+j” method to input them. Here’s a short table on how to enter common unprintable chars:

If you are confused by all these notations, see this article The Confusion of Emacs’s Keystroke Representation for a explanation.

How to change file line endings between Mac/Dos/Unix?

Open the file, then do “Alt+x set-buffer-file-coding-system” (Ctrl+x Enter f). When it prompts you for a coding system, type one of: “mac”, “dos”, “unix”. Then, when you save the file, it’ll be saved with the proper encoding for newlines.

Note: Unixes (including Linuxes and Mac OS X) uses LF (ascii 10; line feed) for newline. Mac OS Classic uses CR (ascii 13; carriage return) for newline. (Mac OS X prefers LF but accepts CR too) Windows uses CR followed by LF (“\r\n”) for its newline char. See wikipedia newline for detail.

To do it batch on a list of files, use the following lisp code:

(defun to-unix-eol (fpath)
“Change file’s line ending to unix convention.”
(let (mybuffer)
(setq mybuffer (find-file fpath))
(set-buffer-file-coding-system ‘unix) ; or ‘mac or ‘dos
(save-buffer)
(kill-buffer mybuffer)
)
)(mapc ‘to-unix-eol
(list
“~/jane/myfile1″
“~/jane/myfile2″
“~/jane/myfile3″
; …
)
)

 

To use the code, first edit the list of files above. Then, select all the code, type “Alt+x eval-region”. That’s it.

If you want the function to work on marked files in dired, then use the following code:

(defun dired-2unix-marked-files ()
“Change to unix line ending for marked (or next arg) files.”
(interactive)
(mapc ‘to-unix-eol (dired-get-marked-files))
)

Select the code and do “Alt+x eval-region”, then “Alt+x dired”, then press “m” to mark the files you want, then do “Alt+x dired-dos2unix-marked-files”.

Link: http://xahlee.org/emacs/emacs_adv_tips.html

1. Get bored and thenfrustated with windows over the appearances and customization options of windows. usually after seeing the screenshot by people using linux.

2. Download a open source version of linux (Fedora , Ubuntu or opensuse) install it, update it add all repositories customise it to minimal level.

3. Reward youself for the good work with some entertainment like movie etc

4. Be reminde by someone of setain work/assignment need you to use a certain software. In general you will be familiar with the windows version of software.

5. Boot back with windows to avoid the painful procedure to lean new command.

6. remain in windows till step 1 repeats. and so the next steps follow.

Finally the virtual OS came to rescue no need to dual boot i guess. thanks to those with the briliant idea (This is not a new concept but i have finaly tried this out so just blogging i guess… ).

Finally i am trying to get things done by making use of the open source community.  Presently i am using windows XP as host and Ubuntu as guest. One can use VirtualBox by Sun to install the guest OS. its pretty cool much more easy to use and install the than the original dual boot installation and no more problem with the grub being corrupted.  I got too  fond of  Emacs, its simply brilliant.

Ok… its time to get back to my work  will blog soon .. hope fully.

New job , new place new people but same old me (or was it ?). The key to success is how adaptable you are to the new environment. It was first exposure to professional environment and i was stuck up with the old trick and that lead to confusion and poor communication. I realize that when and journey ends you need to spent sometime with your self to make a mental note of what one has learned from it enjoy the happy moments and remember the hard times. Rethink about the relationships. and be prepared for the new journey ahead.

Unfinished blog will update next time …

I had to rule out that the problem was due to network issues as even coping files from one partition to other gave interrupts. I searched some diagnostic tools from Seagate, … but before I used the tools i simply used S (out of sheer laziness as I didn’t want to go out and buy a floppy or CD which was required). The scan ran endlessly partition by by partition till eternity., so i was pretty sure it was a problem lies with the hard disk. the scan did correct some error but did not improve the performance still interrupts were high whenever HD was accessed.

Now finally the solution:
Just before i set out for buying the floppy/CD or formatting by complete my HD( which i was thinking about but was planning to avoid). I finally decided to just change the port from SATA1 to SATA2. And there you go problem solved …..

So solution was simple but before I could solve i had to do all the above stuff and had to suffer with problem for a entire week when even playing songs was not possible ( the voice used to break due to high interrupt in between and it was so irritating). So be it Life is always like that…
]]> http://chiddu.wordpress.com/2008/06/22/high-cpu-usage-due-to-interrupts/feed/ 0 chiddu http://chiddu.wordpress.com/2008/06/16/referenceguide/ http://chiddu.wordpress.com/2008/06/16/referenceguide/#comments Mon, 16 Jun 2008 18:24:00 +0000 chiddu http://chiddu.wordpress.com/2008/06/16/referenceguide/ ]]> General information about anything:

1. Wikipedia

Technology related to computers :

1. Techtree
2. Tech2

Information about latest games:

1. Gamespot