For basic usage of a command line shell, it is good to know about programs provided by the coreutils package.
The GNU Core Utilities are the basic file, shell and text manipulation utilities of the GNU operating system. These are the core utilities which are expected to exist on every operating system.
Commonly used tools provided by this package include:
ls - list directory contents
ls - copy files and directories
mv - move (rename) files
rm - remove (deletes) files
mkdir - create directories
rmdir - remove empty directories
ln - creates file links
chmod - changes file modes/permissions
chown - change file owner and group ownership
touch - changes file timestamps or create empty files
dd - copies and converts a file
df - shows disk free space on filesystems
du - shows disk usage on filesystems
chroot - Changes the root directory.
Find, search, replace, compare, manipulate text, and basic shell scripting functions
echo - Prints a line of text.
cat - print (and concatenate) files to the standard output
tee - Sends output to multiple files.
head - output the first part of files
tail - output the last part of files
sort - sort lines of text files
tr - translate or delete characters
cut - remove sections from each line of files
uniq - remove duplicate lines from a sorted file
wc - print the number of bytes, words, and lines in files
basename - strip directory and suffix from filenames
dirname - Removes the last level or filename from a given pathname.
seq - Print numeric sequences.
sleep - Suspends execution for a specified time.
true - Returns a successful exit status.
false - Returns an unsuccessful exit status.
md5sum.1 - compute and check MD5 message digest
paste - merge lines of files
join - join lines of two files on a common field
comm - compare two sorted files line by line
fmt - simple optimal text formatter
yes - Print a string repeatedly.
fold - wrap each input line to fit in specified width
pr - convert text files for printing
split - split a file into pieces
hostname - Print or set the machine name.
uname - Print system information.
date - Prints/sets the system date and time.
pwd - Print the current working directory.
nice - Modify scheduling priority.
who - Print a list of all users currently logged in.
groups - Print the groups that the user is a member of.
whoami - Print effective user id.
env - Displays/modifies the environment.
Other coreutils commands include dir, dircolors, install, link, mkfifo, mknod, shred, sync, unlink, vr, chgrp, expr, factor, hostid, logname, nohup, patchk, pinky, printenv, printf, stty, tty, users, cksum, csplit, nl, od, ptx, sum, tac, tsort
Previously these utilities were offered as three individual sets of GNU utilities, fileutils, shellutils, and textutils. Those three have been combined into a single set of utilities called the coreutils.
Debian Woody shipped with the fileutils, shellutils, and textutils packages. Sarge shipped with coreutils. In Sarge and Etch the fileutils, shellutils, and textutils were dummy transition packages to facilitate uggrades. In Etch and later they may be safely removed.