This page contains an overview of commands that we will be using during the labs. It is supposed to be used as a starting point: when you know what to do but do not know which command solves this task. Use the provided links or your local manpage to learn more about the command.
The provided examples shall work out-of-the box on any reasonably recent GNU/Linux machine.
Commands: bc, cat, cd, cp, cut, echo, grep, head, ls, mkdir, paste, pwd, rm, rmdir, sort, tail, test, touch, tr, uniq, wc.
bc: arithmetic language processor (calculator)
man 1 bc
(man7.org,
linux.die.net).
echo "for (x=0; x<10; x++) {random();}" | bc
bc ~/arithmetic-computation
cat: concatenate and print files
man 1 cat
(man7.org,
linux.die.net).
cat /etc/passwd cat /etc/passwd - /etc/group
cd: change the current (working) directory
man 1p cd
(man7.org,
linux.die.net).
cd cd /etc
cp: copy files and directories
man 1 cp
(man7.org,
linux.die.net).
cp /etc/passwd . cp /etc/passwd ~/passwords.backup cp -r /etc/default defaults_copy
cut: print parts of lines
man 1 cut
(man7.org,
linux.die.net).
cut -d: -f 1,5-7 /etc/passwd
echo: write arguments to standard output
man 1 echo
(man7.org,
linux.die.net).
echo echo -n Hello echo Printing Hello World to screen
grep: print lines containg given expression (either searches for a normal string with -F or uses a full-fledged regular expression (regex)).
man 1 grep
(man7.org,
linux.die.net).
grep -F system /etc/passwd grep --color=auto system /etc/passwd grep ':[0-9][0-9][0-9]:' /etc/passwd
head: print beginning of files
man 1 head
(man7.org,
linux.die.net).
head /etc/passwd head -n2 /etc/passwd /etc/group
ls: list directory contents (files, their modification time etc.)
man 1 ls
(man7.org,
linux.die.net).
ls ls /etc ls /proc/1/fd
mkdir: create (make) directories
man 1 mkdir
(man7.org,
linux.die.net).
mkdir dir1 dir2 dir3 mkdir -p dir1/dir2/dir3
paste: merge lines of files together
man 1 paste
(man7.org,
linux.die.net).
paste /etc/passwd /etc/group paste -d+ /etc/passwd/ /etc/group cut -d: -f 3 /etc/passwd | paste -s -d+
pwd: print current (working) directory
man 1 pwd
(man7.org,
linux.die.net).
pwd
rm: remove files and directories
man 1 rm
(man7.org,
linux.die.net).
rm ~/passwords.backup rm -r dir1 rm /proc/1/status
rmdir: remove directories
man 1 rmdir
(man7.org,
linux.die.net).
rmdir dir1 rmdir /etc rmdir -p dir1/dir2
sort: sort lines
man 1 sort
(man7.org,
linux.die.net).
sort /etc/group sort -n -t: -k3 /etc/passwd
tail: print the last part of file(s)
man 1 tail
(man7.org,
linux.die.net).
tail -n 5 /etc/passwd /etc/shadow tail -q -f /etc/group
test: compare values, check file types, useful for conditions (also [)
man 1 test
(man7.org,
linux.die.net).
test 5 -gt 2; echo $? test 2 -gt 5; echo $? [ 5 -gt 2 [ 5 -gt 2 ]; echo $? test -f /etc/passwd
touch: change (updates) file timestamps, also creates new file
man 1 touch
(man7.org,
linux.die.net).
touch ~/touch.example.txt touch ~/.bashrc touch /etc/passwd
tr: translate (replace) or remove characters (letters)
man 1 tr
(man7.org,
linux.die.net).
tr ':' ' ' </etc/passwd tr -d '/' </etc/passwd tr 'a-z' 'A-Z' </etc/passwd
uniq: find unique or repeated lines (or count them)
man 1 uniq
(man7.org,
linux.die.net).
getent passwd | cut -d : -f 7 | sort | uniq getent passwd | cut -d : -f 7 | sort | uniq -c
wc: count words, lines and bytes in a file
man 1 wc
(man7.org,
linux.die.net).
wc </etc/passwd wc /etc/passwd wc -l </etc/passwd