LPI Linux Certification/Perform Basic File Management
Detailed Objective
edit(LPIC-1 Version 5.0)
Weight: 4
Description: Candidates should be able to use basic Linux commands to manage files and directories.
Key Knowledge Areas:
- Copy, move and remove files and directories individually.
- Copy multiple files and directories recursively.
- Remove files and directories recursively.
- Use simple and advanced wildcard specifications in commands.
- Use
find
to locate and act on files based on type, size, or time. - Usage of
tar
,cpio
anddd
.
The following is a partial list of the used files, terms and utilities:
cp
find
mkdir
mv
ls
rm
rmdir
touch
tar
cpio
dd
file
gzip
gunzip
bzip2
xz
unxz
- file globbing
Create and Remove directories
editTo create a directory, use mkdir.
mkdir [options] dir
Common options:
-m mode: set permission mode. Default use umask. -p parent: create parent directory as needed.
Examples:
mkdir -m 0700 bin mkdir -p bin/system/x86
To delete an empty directory, use rmdir.
rmdir [options] dir
Common options:
-p parent: remove empty superdirectories.
Examples:
rmdir tmp rmdir -p bin/system/x86
Copy files and directories
editTo copy one file to another, or to a directory, use cp.
cp [options] source target
Source and target can be a file or a directory.
Common options:
-i interactive: prompt to overwrite -r recursive: copy the subdirectories and contents. Use -R for special files. -f force: force the overwriting
The default is to silently clobber the target file. (This does not alter the source.
Examples:
cp *.[a-z] /tmp cp readme readme.orig cp ls /bin cp -ri bin/* /bin
Move & Rename files
editTo rename a file or directory or to move a file or directory to another location, use mv.
mv [options] source target
Source and target can be a file or a directory.
Common options:
-i interactive: prompt to overwrite -f force: force the overwriting -v verbose
The default is to silently clobber the target file.
Examples:
mv *.[a-z] /tmp mv readme readme.orig mv ls /bin mv -fi bin/* /bin
Listing filenames and information
editThe command to list files in the current directory is ls.
ls [options] [filenames]
Common options are:
-l For a long format -F Append a file type character -a All files, including hidden files -R Recursive listing of subtree -d Do not descend into directory
The ls is equivalent to the dir command on DOS.
Examples of ls output:
$ ls -l /bin/ls -rwxr-xr-x 1 root root 46784 mar 23 2002 /bin/ls $ ls -ld /bin drwxr-xr-x 2 root root 2144 nov 5 11:55 /bin $ ls -a . .bash_history .bash_profile .bashrc ... $ ls -dF /etc .bashrc /bin/ls .bashrc /bin/ls* /etc/
File types
editThe long format means:
$ ls -l /etc/hosts #List a long format of the file hosts -rw-r—r-- 1 root root 677 Jul 5 22:18 /etc/hosts
File content and location Linux/Unix does not distinguish file by filename extension, like Windows. To determine the file content use file.
$ file /etc .bashrc /bin/ls /dev/cdrom /etc: directory .bashrc: ASCII English text /bin/ls: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), stripped /dev/cdrom: symbolic link to /dev/hdc
To determine if a command is a built-in shell command or a program, use type, and use which to find its location.
$ type cp cd ls which type cp is /bin/cp cd is a shell builtin ls is aliased to `ls $LS_OPTIONS' which is aliased to `type -p' type is a shell builtin $ which cut /usr/bin/cut
Creating and using filenames
editFilenames can be created with:
- I/O redirection
cat chapter1 chapter2 > book
- An editor, such as vi.
vi mynewfile
- Many of the Unix utilities
cp file newfile
- An application
netscape
- The touch command, which creates empty files (or updates the "date modified" of existing files)
touch memo
The valid filename may have (or be):
- Maximum 255 characters per filename
- Any character except forward '/'
- Recommended alphanumeric characters as well as plus, minus, and underscore characters.
- Case sensitive ('A' and 'a' are treated differently)
Characters to avoid
- Hyphen character.
touch my-file -lt
- White space.
touch more drink touch "more drink"
- Most other special characters !@#$%^&*():;"'}{|\<,>.?~`
touch memo*
Remove files or directories
editTo remove files or subtree directories, use rm.
rm [options] files
Files can be a file or a directory.
Common options:
-i interactive: prompt for each removal -f force: force the overwriting -r recursive: remove subtree directories and contents
There is no 'unremove' or 'undelete' command.
Examples:
rm *.[a-z] rm readme readme.orig rm ls /bin rm -rfi /bin cd; rm -rf * .* # This removes all files in the home directory of the current user, as well as those in the subdirectories therein!
Locating files in a subtree directory
editTo search for a file in a subtree directory, use find.
find [subtrees] [conditions] [actions]
The command can take multiple conditions and will search recursively in the subtree.
Some possible conditions are:
-name [FNG] # Search for the FNG name -type c # Type of file [bcdfl] -size [+-]# # Has a +- size in blocks (c: bytes, k: kilobytes) -user [name] # Own by user -atime [+-]# # Accessed days ago. +n means the file has not been accessed for the last n days. -n means the file has been accessed in the last n days. -mtime [+-]# # Modified days ago -perm nnn # Has permision flags nnn
Some possible actions are:
-print # Print the pathname -exec cmd {} \; # Execute cmd on the file -ok cmd {} \; # Same as -exec but ask first
Examples:
find . -name '*.[ch]' -print find /var /tmp . -size +20 -print find ~ -type c -name '*sys*' -print find / -type f -size +2c -exec rm -i {} \; find / -atime -3 -print find ~jo ~toto -user chloe -exec mv {} /tmp \;
To locate a binary, source file, or man page, use whereis.
whereis [options]
Common options:
-b: Search only for binaries. -m: Search only for manual sections. -s: Search only for sources.
Examples:
$ whereis host host: /usr/bin/host /etc/host.conf /usr/share/man/man1/host.1.gz $ whereis -m host host: /usr/share/man/man1/host.1.gz
To locate a file located somewhere defined by the PATH variable, use which.
$ which -a ls /bin/ls
The -a will look for all possible matches in PATH, not just for the first one.
Exercises
edit- Compose an interactive command to remove all .tmp files in your home directory. Respond y to every prompt.
- List all the files in the user's home directories ending with .pdf that are bigger than 50 blocks and have not been accessed for a month.
- Create a file file.h that will contain all the filenames ending with .h found in the /usr directory.
- Do a touch on all the c files found in /usr/src/packages directory.
- What are the default permissions when you create a new file and a new directory?
- How would you create a new file or directory that contains a space in the filename? (Example: 'new dir')
- What is the command to remove all the files of types char and block in your home directory?
- How would you find the location of the program find?
- Delete all files in /tmp which are not owned by root and have not been accessed for a week.