Find (search) and replace text from command line in multiple files (Linu

August 11, 2012 - 4:18pm - by admin

Another (and more easy) way to change text in multiple files is to use grep:

grep -lr -e 'oldtext' * | xargs sed -i 's/oldtext/newtext/g'

or to use PERL:

perl -p -i -e ’s/oldtext/newtext/g’ *

 

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Find (search) and replace text from command line in multiple files (Linu

August 11, 2012 - 3:23pm - by admin

Just after I posted this article the second more easy solution has been found. Here it is:

Find (search) and replace text from command line in multiple files (Linux) #2

When you are working on the Linux command line and you come across a large file or a large number of files in which you need to replace a certain text with another, finding and pasting over each instance of the text can be a bit time consuming. Well, worry no more. Linux has just the solution for you. Here’s a way to find and replace a string of text in one or more files automatically.

For the purpose of this exercise we will use a Linux command line tool called “sed”.  ”sed” is a very powerful and versatile tool, and a lot can be written about its capabilities. We are using a very limited aspect of “sed” here. I would definitely recommend that you read up a little more on “sed” if you find this aspect of it interesting.

We are going to use the following syntax to find and replace a string of text in a file:

# sed -i 's/[orginal_text]/[new_text]/' filename.txt

Say you have a file called “database.txt” with numerous instances of the IP address of your database server in it. You have just switched to a new database server and need to update it with the new server’s IP address. The old IP address is 192.168.1.16 and the new one is 192.168.1.22. Here’s how you go about it:

# cat database.txt

LOCAL_DATABASE = 192.168.1.16

LOCAL_DIR = /home/calvin/

PROD_DB = 192.168.1.16

# sed -i 's/192.168.1.16/192.168.1.22/g' database.txt

# cat database.txt

LOCAL_DATABASE = 192.168.1.22

LOCAL_DIR = /home/calvin/

PROD_DB = 192.168.1.22

Now open the file “database.inc” and check to see if the new IP address has taken place of your old one. Here’s the breakup of the above command. First you call the “sed” command. Then you pass it the parameter “-s” which stands for “in place of”. Now we use a little bit of regular expressions, commonly known as “regex”  for the next bit. The “s” in the quoted string stands for “substitute”, and the “g” at the end stands for “global”. Between them they result in a “global substitution of the the string of text you place in between them.

You can optionally skip the “g” at the end. This means that the substitution will not be global, which practically translates to the substitution of only the first instance of the string in a line. So if you had a line with multiple instances of the text you are trying to replace, here’s what will happen

# cat database.txt

LOCAL_DATABASE = 192.168.1.16

LOCAL_DIR = /home/calvin/

PROD_DB = 192.168.1.16, 192.168.1.16

# sed -i 's/192.168.1.16/192.168.1.22/' database.txt

# cat database.txt

LOCAL_DATABASE = 192.168.1.22

LOCAL_DIR = /home/calvin/

PROD_DB = 192.168.1.22, 192.168.1.16

Here comes the real magic. Now, say you want to change a string of text not just in a single file, but in the entire directory you are in. There are a number of text files in which you need to find and replace the “wine” with “champagne”.

# find . -maxdepth 1 -name "*.txt" -type f -exec sed -i 's/wine/champagne/' {} \

We use the find command to get a list of all the text files in the current directory. That’s the “find . -maxdepth 1 -name “*.txt” -type f” part. “find . maxdepth 1″ tell the computer to look in the current directory and go no deeper than the current directory. The ‘-name  ”*.txt”‘ part tells find to only list files with the extension of “.txt”. Then the “-type f” section specifies that “find” should only pick exactly matching files. Finally the “-exec” part tells “find” to execute the command that follows, which, in this case, is the “sed” command to replace the text – “sed -i ‘s/wine/champagne/’ {} \”.

I realize that the above command seems complicated. However, once you use it a little bit you will realize that it is probably worth noting it down and using it. Now try changing a string of text in multiple levels of directories.

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Disable automatic unzipping on file download in Safari (Mac OS X)

August 11, 2012 - 2:02pm - by admin

After file downloading a ZIP file with Safari this file is unzipped automatically. The original ZIP file appears to be deleted. Not so good!

To fix this behaviour just go to

Safari->Preferences->General

and uncheck "Open Safe Files After Downloading".

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Date format validation in PHP

July 19, 2012 - 1:25pm - by admin

In case of date format checking in PHP just use this function:

function checkDateFormat($date)

{

  //match the format of the date

  if (preg_match ("/^([0-9]{4})-([0-9]{2})-([0-9]{2})$/", $date, $parts))

  {

    //check weather the date is valid of not

        if(checkdate($parts[2],$parts[3],$parts[1]))

          return true;

        else

         return false;

  }

  else

    return false;

}

Example:

echo checkDateFormat("2008-02-29"); //return true

echo checkDateFormat("2007-02-29"); //return false

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Mac OS, MySQL: No such file or directory (trying to connect via unix:///

July 18, 2012 - 6:51pm - by admin

Error on attempt to connect locally to MySQL server DB with PHP on MacOS X Lion 10.7:

No such file or directory (trying to connect via unix:///var/mysql/mysql.sock)

Solution 1:

instead of localhost use 127.0.0.1:

mysql_connect ('127.0.0.1', $user, $password);

Solution 2:

In /etc/php.ini change

pdo_mysql.default_socket = /var/mysql/mysql.sock

mysql.default_socket = /var/mysql/mysql.sock

mysqli.default_socket = /var/mysql/mysql.sock

to

pdo_mysql.default_socket = /tmp/mysql.sock

mysql.default_socket = /tmp/mysql.sock

mysqli.default_socket = /tmp/mysql.sock

Do not forget to restart Apache after update :-)

FYI: If no /etc/php.ini found just copy /etc/php.ini.default to /etc/php.ini

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MySQL: ERROR 2006 (HY000) at line: ### MySQL server has gone away

July 18, 2012 - 6:11pm - by admin

In case of MySQL error 2006 (HY000) at line: ### MySQL server has gone away which may occur while restoring a big DB dump just add (or increase, if exists) max_allowed_packet parameter of MySQL config (usually in /etc/my.cnf).

For example:

[mysqld]

max_allowed_packet=128M

And do not forget to restart MySQL server :-)

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GIT: How to use stash

December 22, 2011 - 7:41am - by admin

Git features The Stash, which is as much as a good place to store uncommitted changes. When you stash you changes, the will be stored, and your working copy will be reverted to HEAD (the last commit revision) of your code.

When you restore your stash, you changes are reapplied and you continue working on your code.

Stash your current changes

$ git stash save 

Saved "WIP on master: f12345..."

List current stashes

Yes, you can have more than one!! The stash works like a stack. Every time you save a new stash, it's put on top of the stack.

$ git stash list

stash@{0}: WIP on master: f12345..."

Note the stash@{0} part? That's your stash ID, you'll need it to restore it later on. Let's do that now. The stash ID changes with every stash you make. stash@{0} refers to the last stash you made.

Apply a stash

$ git stash apply stash@{0}

You may notice the stash is still there after you have applied it. You can drop it if you don't need it any more.

$ git stash drop stash@{0}

Or, because the stash acts like a stack, you can pop off the last stash you saved:

$ git stash pop

If you want to wipe all your stashes away, run the 'clear' command:

$ git stash clear

It may very well be that you don't use stashes that often. If you just want to quickly stash your changes to restore them later, you can leave out the stash ID.

$ git stash

...

$ git stash pop

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IBM ThinkVantage System Update Failure

December 21, 2011 - 12:11pm - by admin

Error:

I have got "Unable to connect to proxy server" error while running IBM Think Vantage System Update. OS is Windows 7.

Fix:

Internet Explorer: Tools => Internet Options => Connections => Lan Settings: uncheck "Use a Proxy Server" and "Use automatic configuration script"

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Git Cheat Sheet

December 12, 2011 - 9:19am - by admin

Configuration

identify yourself to git: email and your name

git config --global user.name "John Smith"

git config --global user.email "abc@mail.com"

To view all options:

git config --list

OR

cat .git/config

Set up aliases

git config --global alias.co checkout

View your configuration

cat .gitconfig

To ignore whitespace (Ruby is whitespace insensitive)

git config --global apply.whitespace nowarn

Some nice aliases:

gb = git branch
gba = git branch -a
gc = git commit -v
gd = git diff | mate
gl = git pull
gp = git push
gst = git status

Start using git

git init

Ignoring files

Add a file in the root directory called .gitignore and add some files to it: (comments begin with hash)

*.log db/schema.rb db/schema.sql

Git automatically ignores empty directories. If you want to have a log/ directory, but want to ignore all the files in it, add the following lines to the root .gitignore: (lines beginning with ‘!’ are exceptions)

log/*
!.gitignore

Then add an empty .gitignore in the empty directory:

touch log/.gitignore

Scheduling the addition of all files to the next commit

git add .

Checking the status of your repository

git status

Committing files

git commit -m "First import"

Seeing what files have been committed

git ls-files

Scheduling deletion of a file

git rm [file name]

Committing all changes in a repository

git commit -a

Scheduling the addition of an individual file to the next commit

git add [file name]

Viewing the difference as you commit

git commit -v

Commit and type the message on the command line

git commit -m "This is the message describing the commit"

Commit and automatically get any other changes

git commit -a

A “normal” commit command

git commit -a -v

Viewing a log of your commits

git log

Viewing a log of your commits with a graph to show the changes

git log --stat

Viewing a log with pagination

git log -v

Visualizing git changes

gitk --all

Creating a new tag and pushing it to the remote branch

git tag "v1.3"
git push --tags

Creating a new branch

git branch [name of your new branch]

Pushing the branch to a remote repository

git push origin [new-remote]

Pulling a new branch from a remote repository

git fetch origin [remote-branch]:[new-local-branch]

Viewing branches

git branch

Viewing a list of all existing branches

git branch -a

Switching to another branch

The state of your file system will change after executing this command.

git checkout [name of the branch you want to switch to]

OR

git co [name of the branch you want to switch to]

Making sure changes on master appear in your branch

git rebase master

Merging a branch back into the master branch

First, switch back to the master branch:

git co master

Check to see what changes you’re about to merge together, compare the two branches:

git diff master xyz

If you’re in a branch that’s not the xyz branch and want to merge the xyz branch into it:

git merge xyz

Reverting changes to before said merge

git reset --hard ORIG_HEAD

Resolving conflicts

Remove the markings, add the file, then commit.

Creating a branch (and switching to the new branch) in one line

git checkout -b [name of new branch]

Creating a stash (like a clipboard) of changes to allow you to switch branches without committing

git stash save "Put a message here to remind you of what you're saving to the clipboard"

Switching from the current branch to another

git co [branch you want to switch to]

Do whatever
Then switch back to the stashed branch

git co [the stashed branch]

Viewing a list of stashes

git stash list

Loading back the stash

git stash apply

Now you can continue to work where you were previously.

Deleting a branch (that has been merged back at some point)

git branch -d [name of branch you want to delete]

Deleting an unmerged branch

git branch -D [name of branch you want to delete]

Deleting a stash

git stash clear

Setting up a repository for use on a remote server

Copy up your repository. e.g.:

scp -r my_project deploy@yourbox.com:my_project

Move your files on the remote server to /var/git/my_project
For security make the owner of this project git
On the repository server:

sudo chown -R git:git my_project

Then (for security) restrict the “deploy” user to doing git-related things in /etc/passwd with a git-shell.

Checking out a git repository from a remote to your local storage

git clone git@yourbox.com:/var/git/my_project

Viewing extra info about a remote repository

cat .git/config

By virtue of having cloned the remote repository, your local repository becomes the slave and will track and synchronize with the remote master branch.

Updating a local branch from the remote server

git pull

Downloading a copy of an entire repository (e.g. laptop) without merging into your local branch

git fetch laptop

Merging two local branches (ie. your local xyz branch with your local master branch)USE MERGE

git merge laptop/xyz

This merged the (already copied laptop repository’s xyz branch) with the current branch you’re sitting in.

Viewing metadata about a remote repository

git remote show laptop

Pushing a committed local change from one local branch to another remote branch

git push laptop xyz

Creating a tracking branch (i.e. to link a local branch to a remote branch)

git branch --track local_branch remote_branch

You do not need to specify the local branch if you are already sitting in it.

git pull

Note: You can track(link) different local branches to different remote machines. For example, you can track your friend’s “upgrade” branch with your “bobs_upgrade” branch, and simultaneously you can track the origin’s “master” branch (of your main webserver) with your local “master” branch.

By convention, ‘origin’ is the local name given to the remote centralized server which is the waySVN is usually set up on a remote server.

Seeing which local branches are tracking a remote branch

git remote show origin

Working with a remote Subversion repository (but with git locally)

git-svn clone [http location of an svn repository]

Now you can work with the checked out directory as though it was a git repository. (cuz it is)

Pushing (committing) changes to a remote Subversion repository

git-svn dcommit

Updating a local git repository from a remote Subversion repository

git-svn rebase

NOTE: make sure you have your perl bindings to your local svn installation.

I screwed up, how do I reset my checkout?

git checkout -f

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How to copy / paste text in gitk

December 2, 2011 - 9:17am - by admin

Problem:

How to copy / paste text from git?

Text select and Ctrl-C + Ctrl-V does not paste the copied text. And there is no Edit / Copy / Paste menu item.

Solution:

gitk supports the normal X clipboard, thus

1. 1. Select text, Ctrl-C to copy.


2. 2. Paste text into X terminal window used to start gitk ! It does paste here.


3. 3. Next do copy / paste again to any of your editor / tool.

Voila !

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