Difference between revisions of "Core utilities"

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m (ls: use newer syntax to avoid awkward over-explaining)
(Extracting compressed files: sub shell not needed)
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           *)    echo "$0: cannot extract \`$1': Unrecognized file extension" >&2; e=1 ;;
 
           *)    echo "$0: cannot extract \`$1': Unrecognized file extension" >&2; e=1 ;;
 
         esac
 
         esac
         [[ $c ]] && `command $c "$1"`
+
         [[ $c ]] && command $c "$1"
 
       else
 
       else
 
         echo "$0: cannot extract \`$1': File either does not exist or is unreadable" >&2; e=2
 
         echo "$0: cannot extract \`$1': File either does not exist or is unreadable" >&2; e=2

Revision as of 10:46, 16 January 2010

This article deals with so-called "core" utilities on a GNU/Linux system, such as less, ls, and grep. The scope of this article includes -- but is not limited to -- those utilities included with the GNU Template:Package Official package. What follows are various tips and tricks and other helpful information related to these utilities. If sections grow too detailed, please split into separate articles.

This page is currently under construction.

See also:

alias

alias is a command in various shells, such as Bash, which enables a replacement of a word with another string. It is mainly used for abbreviating a system command, or for adding default arguments to a regularly used command.

Personal aliases are preferably stored in Template:Filename, and system-wide aliases (which affect all users) belong in Template:Filename.

An example excerpt from Template:Filename covering several time-saving aliases: Template:File

Extracting compressed files

The following function will extract a wide range of compressed file types. Add the function to Template:Filename and use it with the syntax Template:Codeline

Template:File

Note: make sure extglob is enabled: Template:Codeline. It is enabled by default if using Bash completion.

grep

grep is a command line text search utility originally written for Unix. The Template:Codeline command searches files or standard input globally for lines matching a given regular expression, and prints them to the program's standard output.

Colored output

Beyond aesthetics, Template:Codeline's color output is immensely useful for learning Template:Codeline and Template:Codeline's functionality.

To add it, write the following entry to Template:Filename:

export GREP_COLOR="1;33"
alias grep='grep --color=auto'

The variable Template:Codeline is used to specify the output color, in this example a light yellow color.

Although Template:Codeline's man page states that Template:Codeline is deprecated and that Template:Codeline is preferable, this variable does not work as of Template:Package Official version 2.5.4, so use Template:Codeline for now.

less

less is a terminal pager program used to view the contents of a text file one screen at a time. Whilst similar to other pages such as Template:Codeline and Template:Codeline, Template:Codeline offers a more advanced interface and complete feature-set.[1]

Browsing compressed files

Frequent users of the command line interface might want to install Template:Package Official:

# pacman -S lesspipe

Users may now list the compressed files inside of an archive using their pager:

Template:Command

Template:Codeline also grants Template:Codeline the ability of interfacing with files other than archives; serving as an alternative for the specific command associated for that file-type (such as viewing Template:Filename via Template:Package Official).

Re-login after installing Template:Codeline in order to activate it, or source Template:Filename.

ls

ls is a command to list files in Unix and Unix-like operating systems.

Colored output

File Template:Filename should already have the following entry copied from Template:Filename:

alias ls='ls --color=auto'

The next step will further enhance the colored Template:Codeline output; for example, broken (orphan) symlinks will start showing in a red hue. Add the following to Template:Filename and relogin, or source the file:

eval $(dircolors -b)