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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 GNUpackage. 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.
grep is a command line text search utility originally written for Unix. The
grep command searches files or standard input globally for lines matching a given regular expression, and prints them to the program's standard output.
grep's color output is immensely useful for learning
To use the default colors for grep, write the following entry to
alias grep='grep --color=auto'
To include file line numbers in the output, add "-n":
alias grep='grep -n --color=auto'
The environment variable
GREP_COLORS may be used to specify different colors than the defaults.
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
less offers a more advanced interface and complete feature-set.
You can enable code syntax coloring in
less. First, install .
Then add these lines to your
export LESSOPEN="| /usr/bin/source-highlight-esc.sh %s" export LESS=' -R '
Frequent users of the command line interface might want to install:
# pacman -S lesspipe
Users may now list the compressed files inside of an archive using their pager:
$ less compressed_file.tar.gz
==> use tar_file:contained_file to view a file in the archive -rw------- username/group 695 2008-01-04 19:24 compressed_file/content1 -rw------- username/group 43 2007-11-07 11:17 compressed_file/content2 compressed_file.tar.gz (END)
lesspipe also grants
less 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 HTML via ).
Re-login after installing
lesspipe in order to activate it, or source
ls is a command to list files in Unix and Unix-like operating systems.
Colored output can be enabled with a simple alias. File
~/.bashrc should already have the following entry copied from
alias ls='ls --color=auto'
The next step will further enhance the colored
ls output; for example, broken (orphan) symlinks will start showing in a red hue. Add the following to
~/.bashrc and relogin, or source the file:
eval $(dircolors -b)