Linux Commands Part 1 - 4
Tags: linux-com-book
Introductory Commands
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before terminal means super-userdate
to print date and timeSat Jun 18 12:01:17 AM IST 2022
cal
to print calendardf
to print disk drive and usagefree
to print memorypwd
print working directoryAbsolute PathName
: begins with root directory and follows the tree branch by branch till the desired folderRelative PathName
: starts from the working directorycd
to change directorycd -
to revert to previous directorycd ~username
: to change directory to another user
ls : to list directories
ls directory_1 directory_2
: to print list or multiple directories
ls -l
: for more detailsls -lt
: to list sorted acc. date modifed—reverse
: to reverse the sort
Long Listing Details
file filename
: to print a brief description of the file’s contentsless
: to view content of file
File Structure
Symbolic Links | Soft Link | Symlink
symbolic links are like aliases or another name for the file
Why they are useful ?
Imagine we have a file with name
foo
. Whenever we update it we, change its name to foo-date-time, but the programs/user referencing it wouldst know that the name has change. To tackle this problem, we create a symlink of file foo → foo-date-time and the programs/user user only reference the symlink.So even if we change the name of file foo, it wont affect the programs as they would be referencing the symlink.
Manipulating Files and Directories
to create new directories
mkdir dir_name
to create multiple directories
mkdir dir1 dir2 dir3
to copy file to another directory
cp item directory
if
cp item1 item2
then content of item2 is replace with item1
use
-a
file while copying to copy the attributes as well
The
mv
command performs both file moving and file renaming, depending on how it is usedto move item to another directory
mv item... directory
to delete item
rm item
Hard Links vs Soft Links
Hard Link
Hard links are the original Unix way of creating links
Every file has a single hard link that gives the file its name
Limitations
A hard link cannot reference a file outside its own file system
A hard link may not reference a directory
A hard link is indistinguishable from the file itself
Soft Link
They work by creating a special type of file that contains a text pointer to the referenced file or directory
They are like windows shortcuts
If file is deleted, then link points to nothing, it is broken
WildCards
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