hello everyone
in the last post, my friend “3abed” talked about Shell and its Advantages, Commands architecture and he also wrote some commands to let you know how to write commands
in this post … we’ll talk about “Getting Help” in shell
but before we start talking about getting help … let me talk about an indispensable command!!!
cd:
this command is used to Change Direcotry and it’s used as follows:
#cd /etc/
ok i want to Change Directory from /etc/ to /etc/sysconfig/
there’re two ways to write the path:
Relative Path:
The path in relation to the current working directory, and it’s used as follows:
#cd sysconfig/
Absolute Path:
The path that you can enter from any directory
#cd /etc/sysconfig/
note:there’s a way of referring to the Parent Directory or the Current Directory
the current directory is reffered to as “.”
the parent directory is referred to as “..”
so we can go to /etc/sysconfig/ from /etc/ by typing:
#cd sysconfig/
or
#cd ./sysconfig/
and we can go back to /etc/ by typing:
#cd ../
and this equals “UP” in any directories browser
if we want to go “back” type:
#cd -
now we can talk about getting Help:
1)man pages:
“man pages” is short to “manual pages“
manual pages are documentation for all Unix and Unix-like operating systems
usage:
you can see the documentation of any command in linux by simply write this:
#man <command>
so if you want to see the “ls” command documentation, you’ll have to write:
#man ls
you’ll find a very good and understandable documentation about the “ls” command
in the “See Also” section, you may find “<command> (2)” ( ex: mkdir (2) )
suppose you want to see the “mkdir” documentation, you’ll find in the “See Also” section a different page for the same command “mkdir (2)”, so you can simply see this page by typing
#man 2 mkdir
notes:
- you can search the man page using “/<search word>” (ex: /any)
- you can go down to the next search keyword by using “n” button, and go up using “Shift+n”
- you can exit man pages using “q” button
2)info pages:
usage:
#info ls
unlike the “man pages”, “info pages” presents the Documentation as a tree
so you can move to tree branches simply, so when you goto info page, you can use the following shortcuts:
- “n” –> goto the next page
- “p” –> goto the previous page
- “u” –> goto the upper page
- “l” –> goto the lower page
3)help option
#ls –help
“help” option shows a fast documentation about commands and its options
it really helps when you’re looking for an option usage
usage:
#ls –help
4)online help:
and this is the most powerful type of “Getting Help” as it contains a very large number of problems and their solutions
you can get help using many sites, ex:
GNU , TLDP and also you can use search engines like “google” and “yahoo”
they’re really useful
5)whatis command:
“whatis” command searches its DataBase that contains short descriptions of system commands
usage:
#whatis ls
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hope this information was useful
any Questions?? post a comment!
thanQ
bye
