Linux1 - Revision history

GethinWilliams at 15:58, 5 July 2010

2010-07-05T15:58:15Z

GethinWilliams: /* Other useful commands.. */

2008-11-19T16:31:39Z

Other useful commands..

GethinWilliams at 16:31, 19 November 2008

2008-11-19T16:31:08Z

GethinWilliams: /* Comparing content */

2008-11-19T16:29:36Z

Comparing content

GethinWilliams: /* Locating files and directories */

2008-11-19T16:10:07Z

Locating files and directories

GethinWilliams: /* A new type of file: symbolic links */

2008-11-18T17:11:29Z

A new type of file: symbolic links

GethinWilliams: /* Searching for things */

2008-11-18T17:10:45Z

Searching for things

GethinWilliams: /* Wild cards and bash completion */

2008-11-18T17:06:19Z

Wild cards and bash completion

GethinWilliams: /* Displaying content */

2008-11-18T17:01:30Z

Displaying content

GethinWilliams: /* Displaying content */

2008-11-18T16:58:29Z

Displaying content

@@ Line 14: / Line 14: @@
 Now that you are logged in a Linux system, it is time to get the practical content. The files for this practical are hosted in a version control system.  To get them, just cut & paste the following onto your command line:
 <pre>
-$ svn export http://source.ggy.bris.ac.uk/subversion-open/linux1/trunk linux1
+$ svn export https://svn.ggy.bris.ac.uk/subversion-open/linux1/trunk linux1
 </pre>

@@ Line 559: / Line 559: @@
 Include:
-* mv: for '''m'''o'''v'''ing/renaming files or directories
+* '''<tt>mv</tt>''': for '''m'''o'''v'''ing/renaming files or directories
 = To go further =

@@ Line 554: / Line 554: @@
 $ ln -s /gsa13/ggjpr/linux1/file2 folder2/newlink
 </pre>
 = To go further =

@@ Line 416: / Line 416: @@
 > I added this into file5.
 </pre>
 We can also use <tt>diff</tt> to compare directories. At the moment <tt>folder1</tt> and <tt>folder3</tt> should be the same. Let's check that:

@@ Line 483: / Line 483: @@
 </pre>
-You have the list of all files containing "nano" on your system.  Unfortunately, the database used by <tt>locate</tt> is not updated very often and it probably would not find new files or folders.  Try to locate the <tt>folder3</tt> for instance.  The database is usually updated daily so <tt>locate</tt> would find your <tt>folder3</t> if you looked tomorrow probably.
+You have the list of all files containing "nano" on your system.  Unfortunately, the database used by <tt>locate</tt> is not updated very often and it probably would not find new files or folders.  Try to locate the <tt>folder3</tt> for instance.  The database is usually updated daily so <tt>locate</tt> would find your <tt>folder3</tt> if you looked tomorrow probably.
 The <tt>find</tt> command can be used to recursively search a given path for a pattern.  For instance, to search recursively, starting from the current directory and looking for the pattern "folder_b", use:

@@ Line 545: / Line 545: @@
 </pre>
-Symbolic links are just "shortcuts" or different addresses/paths to the same content. You can edit <tt>file3</tt> and see the changes in <tt>file1</tt> automatically. the only exception is that you can delete the link (<tt>file3</tt>) and the target will stay.
+Symbolic links are just "shortcuts" or different addresses/paths to the same content. You can edit <tt>file3</tt> and see the changes in <tt>file1</tt> automatically.  The only exception is that you can delete the link (<tt>file3</tt>) and the target will stay.
 To create a symbolic link, the command <tt>ln</tt> is used with the option "-s":

@@ Line 470: / Line 470: @@
 =Searching for things=
-Linux is a powerful environment to sift through many files and directories and find content. It is possible to search for files or directories (i.e. when you know (part of) their names or to search inside them for specific content.
+Linux provides a powerful environment to sift through many files and directories and find content. It is possible to search for files or directories, when you know (part of) their names, or to search inside them for specific content.
 ==Locating files and directories==
-There are two main ways of locating files and directories. the <tt>locate</tt> command can be used to search for whole files of folders containing a particular character string. Try for instance to locate "nano":
+There are two main ways of locating files and directories. the <tt>locate</tt> command can be used to search for whole files of folders containing a particular character string.  Try for instance to locate "nano":
 <pre>
 locate nano
@@ Line 483: / Line 483: @@
 </pre>
-You have the list of all files containing "nano" on your system. Unfortunately, the locate database is not updated very often and it probably would not find new files or folders. Try to locate the <tt>folder3</tt> for instance. The database is usually updated daily so <tt>locate</tt> would find <tt>folder3</t> if you looked tomorrow probably.
+You have the list of all files containing "nano" on your system.  Unfortunately, the database used by <tt>locate</tt> is not updated very often and it probably would not find new files or folders.  Try to locate the <tt>folder3</tt> for instance.  The database is usually updated daily so <tt>locate</tt> would find your <tt>folder3</t> if you looked tomorrow probably.
-The <tt>find</tt> command can be used to recursively search a given path for a pattern. For instance, to search recursively, starting from the current directory and looking for the pattern "folder_b", use:
+The <tt>find</tt> command can be used to recursively search a given path for a pattern.  For instance, to search recursively, starting from the current directory and looking for the pattern "folder_b", use:
 <pre>
 $ find . -name 'folder_b'
@@ Line 522: / Line 522: @@
 </pre>
-To search recursively through folder, use the "-r" option. Attention you need to make sure that the list of things to search through includes folders if you want them to be searched recursively!
+To search recursively through folder, use the "-r" option.  Note that you need to make sure that the list of things to search through includes folders if you want them to be searched recursively!
 <pre>
 bash-3.2$ grep -ri pre f*

@@ Line 434: / Line 434: @@
 =Wild cards and bash completion=
-Before going further, it is time to introduce some f the time savers that make Linux such a powerful development environment. So far you have typed commands and fle names in full but Linux is clever enough to help you along the way either by completing the text for you in a similar way to predictive texting on a mobile phone, or by performing substitutions.
+Before going further, it is time to introduce some time-savers that make Linux a powerful development environment.  So far you have typed commands and fle names in full but Linux is clever enough to help you out, either by completing the text for you in a way you could compare to predictive texting on a mobile phone, or by performing substitutions.
-Completion is done with the tab key. When your press <TAB>, the shell tries to understand what are the possible choices and limits it for you. For instance try to type:
+Completion is done with the tab key.  (Note that we are assuming you are using the <tt>bash</tt> shell here.)  When your press <TAB>, the shell tries to understand what are the possible choices and limits it for you.  For instance try to type:
 <pre>
 ls fi<TAB> # (don't press enter!)
@@ Line 449: / Line 449: @@
 </pre>
-Another time saver is the wildcard written as an asterisk or star "<tt>*</tt>". It basically matches any number of consecutive characters. For instance if you want to update the time stamp on both <tt>file1</tt> and <tt>file2</tt>, you could type either:
+Another time saver is the asterisk wildcard, "<tt>*</tt>".  It matches any number of consecutive characters.  For example, if you want to update the time stamp on both <tt>file1</tt> and <tt>file2</tt>, you could type either:
 <pre>
 $ touch file*
@@ Line 460: / Line 460: @@
 </pre>
-This is very useful way of minimising typing. Another important property: if there is only one directory in a directory, you can simply give the star argument to the <tt>cd</tt> command to go directly into it:
+This is very useful way of minimising the amount of typing that you have to do.  Another important property: if there is only one directory in a directory, you can simply give the star argument to the <tt>cd</tt> command to go directly into it:
 <pre>

@@ Line 394: / Line 394: @@
 </pre>
-When you want access to the whole file, the commands <tt>more</tt> or <tt>less</tt> can be used. They both work in a similar way. As for <tt>info</tt>, <tt>less</tt> is a bit more modern and you can use the p and down arrows to navigate the file. With <tt>more</tt>, use the space bar to go down ne page. Try them both and see what is in the middle of <tt>file2</tt> for instance.
+When you want to view the whole file, the commands <tt>more</tt> or <tt>less</tt> can be used.  They both work in a similar way.  Like <tt>info</tt>, <tt>less</tt> is more modern and you can use the '''p''' and down arrows to navigate the file. When using <tt>more</tt>, use the space bar to go down a page.  Try them both and see what is in the middle of <tt>file2</tt> for instance.
-Attention, displaying content can only be done for text files. '''It will not work for binary files!'''. For instance, there is a word document in the <tt>folder2</tt> directory. Try to print the top of the file with <tt>head</tt> for instance and look at the results... It is actually dangerous to use <tt>cat</tt>, <tt>head</tt> or <tt>tail</tt> with binary files because the random garbage content could actually execute actions on the shell. So avoid looking inside binary files with these simple viewers.
+Note that displaying content can only be done for text files. '''It will not work for binary files!'''. For instance, there is a word document in the <tt>folder2</tt> directory.  Try to view the top of the file with <tt>head</tt> for instance... It is actually dangerous to use <tt>cat</tt>, <tt>head</tt> or <tt>tail</tt> with binary files because the seemingly random characters churned out to the screen could actually execute actions on the shell.  So avoid looking inside binary files with these simple viewers.
 =Comparing content=

@@ Line 368: / Line 368: @@
 =Displaying content=
-Sometimes, you want to look a the content of a file but don't need to edit it. It is possible to display file content on Linux by a range of methods. The command <tt>cat</tt> simply displays the content of a file to the screen. It is quick but not appropriate for large files. <tt>head</tt> and <tt>tail</tt> can be used to look respectively at the top or the end of a file. Both commands usually default to the first or last 10 lines of the file althpugh this can be modified with an optional argument. These commands are very convenient when you know that what you are looking for is at the beginning or at the end of your file.
+Sometimes, you want to look a the content of a file but don't need to edit it. It is possible to display file content on Linux by a range of methods. The command <tt>cat</tt> (short for con'''cat'''enate) simply displays the content of a file to the screen, if it is given a single file.  It is quick but not very convenient for large files! <tt>head</tt> and <tt>tail</tt> can be used to look respectively at the top or bottom of a file.  Both commands usually default to 10 lines of the file, althpugh this can be modified with an optional argument (-n).  These commands are very convenient if you would like to look at a file header or the very last lines written to a file (both quite common situations).
 <pre>
 $ head file2