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If you build web sites and host (or want to host) them on Dreamhost, you will be well aware that at some stage you will be using SSH to log in and out of your hosting server. If you have many sites then this gradually becomes tiresome – especially if you use tools like Capistrano to deploy your applications, as you will constantly have to re-enter your passwords.

Fortunately you can certify your local computer, such that it will automatically enter the SSH password for you. Here are some quick tips on how to do it.

Generate Your Security Keys

Generate your private/public key pair on your local machine, from your home directory:

ssh-keygen -d

Now DON'T enter a password - just press return, otherwise you 
will still need to enter a password, when you log in with SSH.

Set Privileges And Copy The Public Key To Your Server

Use the following command to copy your newly created ~/.ssh/id_dsa.pub file up to the server you wish to remote log in to. Note that this command below will set the permissions both locally and remotely. The remote .ssh/* needs to be set to 0600.

N.B. Replace USERNAME and MY_DOMAIN with your own username and domain.

ssh USERNAME@ftp.MY_DOMAIN.COM 'test -d .ssh || mkdir -m 0700 .ssh ; cat >> .ssh/authorized_keys && chmod 0600 .ssh/*' < ~/.ssh/id_dsa.pub

  Enter the normal USERNAME password.

Log In Using SSH

Now log in using:

ssh USERNAME@ftp.MY_DOMAIN.COM

You shouldn't neet to enter a password.

Taking It Further

To simplify things even further you can modify the ~/.ssh/config file such:

Host NICKNAME
Hostname MY_DOMAIN.COM
User USERNAME

Now you only need to type:

ssh NICKNAME

And you will be automatically logged in.

Using bash scripts to become a more efficient web developer

Here are a few scripts, that I find really useful for speeding up my web development time.

I’ve been building up this list as I needed to use them – so they maybe a little raw.

For example often clients send me images with filenames that don’t match my naming standard, so running the appropriate script really helps keep me focussed on the job in hand and not waste too much time reformatting filenames etc.

Finally if you have any useful little bash scripts why don’t you add them to the comments below?

Bash script to append a .txt extension to a filename

Iterate over the current directory, get all files with .log and append .txt to the end of the entire filename:

for i in *.log*; do mv "$i" "$i.txt"; done

Script to make filenames lowercase

Converts all the file names in a directory and converts them to lowercase.

echo version:

for i in *.log*; do echo mv \"$i\" \"`echo $i| tr [A-Z] [a-z]`\"; done

real version:

for i in *.txt; do mv "$i" "`echo $i| tr [A-Z] [a-z]`"; done

Quick note on how to use grep to search for a string in file

-o print Only the matched parts of a matching line, with each part on a separate line. -H print the filename for each match. -n prefix each line of output with the 1 based line number. -R, -r recursively read all files under subdirectories.

grep -oHnr "some pattern"  *.txt

{txt,log} this globs the file extensions together. 2>/dev/null this passes all errors to a blackhole, so that they won’t be displayed.

grep 123741 ./adapter_logs/*.{txt,log} 2>/dev/null

Find all occurrences of 123741 in all .txt and .log files in all subdirectories.

for i in 'find . -type d'; do grep 123741 $i/*.{txt,log}; done 2>/dev/null

List all files that match this regular expression in the current direcory

All files with the number 5 in their name.

ls | grep -e .*5.*

Bash script to check whether a tag exists in a subversion repository

svn ls http://www.mysvnserver.co.uk/myproject/tags | grep mytag-0.7.0.1/

The [ ] is known as a Test, by default it tests integers Also to end an if statement you use fi

if [ 1 = 1 ] ; then echo YES; else echo NO; fi

if [ "`svn ls http://mysvnserver/mysvnrepository/myproject/tags | grep R-9.20.400.0/`" = "R-9.20.400.0/" ]; then echo YES; else echo NO; fi

Note need the / in the evaluation part of “it-0.9.0.7/”, don’t really need it in grep it-0.9.0.7/

$ if [ "`svn ls http://www.mysvnserver.co.uk/myproject/tags | grep it-0.7.0.1/`" = "it-0.7.0.1/" ]; then echo YES; else echo NO; fi

Quick note on how to increment a variable, in a bash script

j=0; j=$(($j+1))

incrementing in a loop

j=0;for i in *.txt; do echo "some_file_"$j".txt"; j=$(($j+1)); done

Using a bash for loop to list all text files and append whoopee

for i in *.txt; do echo $i"whoopee"; done

Change all filenames to be a specific incremented name, starting from file 16

j=16;for i in *.jpg; do mv "$i" "gallery_"$j".jpg"; j=$(($j+1)); done;ls

Script to loop through all .txt filenames and make them lower case

for i in *.txt; do mv "$i" "`echo $i| tr [A-Z] [a-z]`"; done

Get all JPG files and create the appropriate HTML list tags for them and add them to a file

Create an HTML version:

for i in *.jpg; do echo "\t<li>\r\t\t<img src='images/$i' alt='' />\r\t</li>"; done > list_items.html

Create a HAML version:

for i in *.jpg; do echo "\t%li\r\t\t%img{ :src => 'images/$i', :alt => '' }\r"; done > imgs.haml

Batch change a misspelled filename of certain files, using string replacement

for i in aples*.jpg; do mv $i ${i/aples/apples} ; done

Script to batch create files based on filenames in a file

Create a file called something like “my_files.txt” with the following content:

archive_error_112480_0040.txt archive_error_114390_0043.txt etc…

Commands:

for i in `sed -n -e 'p' my_files.txt`; do mkdir a_test/$i; done
or
while read x; do touch $x; done < my_files.txt
or
cat my_files.txt | xargs touch
(xargs passes each line as an argument into EACH touch)

Using bash Expansions, and allow escapes

-e is an undocumented flag that allows escapes Expansion ${command/parameter/substitution} everything else needs to be escaped.

echo -e ${PATH//\:/\\n}

Executing a .bash_script after making changes

source .bash_profile
or
. .bash_profile

NB: you can ‘include’ other bash .sh scripts in a .bash_profile file by using ’source’ or ‘.’

Quick tip on using curl for downloading files off the web

Use -O to name the remote file, curl will save it locally but remove the rest of the path.

curl -O http://rubyforge-files.ruby-forum.com/rubygems/rubygems-0.9.0.tgz

Bash command for testing the existence of files and directories

If a directory does NOT exist create it

[ -d "/var/cache/git" ] || mkdir /var/cache/git

If a file exists echo a message:

[ -f "./new_file.txt" ] && echo "its there"

Bash command to remove spaces from filenames

for i in *.html; do mv "$i" "`echo $i| tr -d ' '`"; done

replace spaces for underscores

for i in *.html; do mv "$i" "`echo $i| tr ' ' '_'`"; done

Vim regex to replace spaces in images file names of ah HTML page

:%s:\(images\/\)\(\w\+\)\s\(\w\+\.jpg\):\1\2_\3:g

Copy text to the clipboard

echo 'hello world'|pbcopy
cmd + v

Conclusion

Some of these are quite basic but useful none-the-less, please add your own to the comments below. Many thanks, and good luck.

Updated…

Script function for .bash_profile to cd to the last opened finder location

This is a script written by a colleague. James Power. Add the following function to your .bash_profile in Apple OSX. Now open a directory in Finder, then open terminal and type cdf, your terminal will now change directory to the same one as the last Finder opened.

# function to change directory to the one set in the last opened finder.
cdf () {
   currFolderPath=$( /usr/bin/osascript <<"         EOT"
       tell application "Finder"
           try
               set currFolder to (folder of the front window as alias)
           on error
               set currFolder to (path to desktop folder as alias)
           end try
           POSIX path of currFolder
       end tell
            EOT
   )
   echo "cd to \"$currFolderPath\""
   cd "$currFolderPath"
}

Also for a much more comprehensive list of commands check out: http://www.commandlinefu.com/commands/tagged/34/bash

Ruby Rush command-line tool

If you use Ruby maybe check out Rush, it allows you do use Ruby in a bash command-line like way.