Mastering Red Hat Linux 9 [Electronic resources] نسخه متنی

cd name

Changes the directory; the directory name can be in absolute format, such as /etc/xinetd.d, or relative format, such as usr/source.

dir

Lists files in the current directory in a specialized manner; a special version of ls; some Linux distributions set alias dir=ls -l.

ls

Lists the files in the current directory; many switches are available.

pwd

Lists the present working directory, so you know where you are.

cp file1 file2

Copies a file; with appropriate switches, this command can be used to copy the contents of a directory and its subdirectories.

file filename

Determines the file type of the file; options include text, image data, gzip compressed file, cpio archive, mail text, and more.

ln file1 file2

Links two different files. A hard link creates a full copy of the same file; a soft link creates a pointer.

mkdir name

Creates a new directory. The name can be in an absolute or relative path format; using the proper switches, you can even create multiple levels of subdirectories with one command.

mv file1 file2

Deletes and copies a file.

rm filename

Deletes a file; using the right switches, you can delete entire directories and subdirectories. This can be a very dangerous command, especially for the root user.

rmdir dirname

Deletes a directory; using the right switches, you can delete entire directories and subdirectories. By default, the directory must be empty.

touch filename

Creates an empty file with filename.

umask abcd

Sets default permissions for newly created files by that user.

cat filename

Reads the contents of a file; also scrolls one or more text files to a screen. This command can also be used to redirect (>) the contents of an image file, such as the Red Hat installation bootdisk.img, to a floppy device.

head filename

Sends the first few lines of a file to the screen; the default is 10 lines.

less filename

Opens a file in a text-style reader; allows up and down scrolling one screen at a time. vi search commands are allowed.

more filename

Opens a file in a text-style reader; allows scrolling one screen at a time. vi search commands are allowed.

find / -name file -print

Finds the location of the file, starting the search in the root (/) directory. You can use wildcards, and start in other directories.

grep string file

Searches for a text string in the specified file. You can use wildcards to extend the search to a series of files.

locate file

Searches through the slocate database for the location of a specified file. Wildcards are assumed; for example, the locate abc command will also find the location of a file named abcd. The slocate database is refreshed as a default cron job every night.

wc file

Displays the number of lines, words, and characters in a text file.

df

Reports partitions on the current hard disk.

du

Notes file-space usage of each file; includes files in subdirectories.

dumpe2fs device

Lists all information related to the device (e.g., /dev/sdb2).

e2label device label

If you just specify the device (e.g. /dev/hda1), this command returns the current label. Otherwise, it assigns a new label; this should correspond to an entry in /etc/fstab.

fsck device

Checks and repairs a Linux filesystem; you should specify the device associated with an unmounted partition. This command normally detects the filesystem and uses the correct format; otherwise, you can use a command such as fsck.minix device, fsck.ext2 device, or e2fsck device. The last two commands work for both the ext2 and ext3 formats.

mount filesystem device

Mounts a filesystem such as /home on a device such as /dev/hda2.

tune2fs device

Converts a partition from ext2 to ext3.

umount filesystem

Unmounts the specified filesystem, such as /home.

cc

Deletes the current line and moves to insert mode so you can type in a replacement.

cw

Deletes the current word and moves to insert mode so you can type in a replacement.

dd

Deletes the current line.

dw

Deletes the current word.

D

Deletes the remainder of the line, starting with the current position of the cursor.

p

Copies the register, the current contents of the buffer, to the line after the cursor.

:reg

Shows the contents of the register.

u

Undoes the last change.

U

Restores the current line.

nY

Copies n lines into the register. See the p command.

a

Inserts new text after the current location of the cursor.

A

Inserts new text at the end of the current line.

Esc

Returns to command mode.

i

Inserts new text at the current cursor location.

I

Inserts new text at the beginning of the line.

o

Starts a new line after the current line.

O

Starts a new line before the current line.

:!command

Runs the specified shell command. Starts in the directory where you started the vi text editor.

q

Exits the file. If you’ve made changes, you can leave vi without writing those changes with the q! command.

w

Writes the current file.