- Allowed editors: vi, vim, emacs
- All your scripts will be tested on Ubuntu 14.04 LTS
- All your scripts should be exactly two lines long ($ wc -l file should print 2)
- All your files should end with a new line (why?)
- The first line of all your files should be exactly #!/bin/bash
- A README.md file, at the root of the folder of the project, describing what each script is doing
- You are not allowed to use &&, || or ;
- You are not allowed to use bc, sed or awk
- All your files must be executable
- mandatory 0-alias
Create a script that creates an alias.
- Name: ls
- Value: rm *
julien@ubuntu:/tmp/0x03$ ls
0-alias file1 file2
julien@ubuntu:/tmp/0x03$ source ./0-alias
julien@ubuntu:/tmp/0x03$ ls
julien@ubuntu:/tmp/0x03$ \ls
julien@ubuntu:/tmp/0x03$
- Hello you mandatory - 1-hello_you
Create a script that prints hello user, where user is the current Linux user.
julien@ubuntu:/tmp/0x03$ id
uid=1000(julien) gid=1000(julien) groups=1000(julien),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)
julien@ubuntu:/tmp/0x03$ ./1-hello_you
hello julien
julien@ubuntu:/tmp/0x03$
- The path to success is to take massive, determined action mandatory - 2-path
Add /action to the PATH. /action should be the last directory the shell looks into when looking for a program.
julien@ubuntu:/tmp/0x03$ echo $PATH
/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
julien@ubuntu:/tmp/0x03$ source ./2-path
julien@ubuntu:/tmp/0x03$ echo $PATH
/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/action
julien@ubuntu:/tmp/0x03$
- If the path be beautiful, let us not ask where it leads mandatory 3-paths
Create a script that counts the number of directories in the PATH.
julien@ubuntu:/tmp/0x03$ echo $PATH
/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
julien@ubuntu:/tmp/0x03$ . ./3-paths
11
julien@ubuntu:/tmp/0x03$ PATH=/home/julien/bin:/home/julien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:::::/hello
julien@ubuntu:/tmp/0x03$ . ./3-paths
12
julien@ubuntu:/tmp/0x03$
- Global variables mandatory 4-global_variables
Create a script that lists environment variables.
julien@ubuntu:/tmp/0x03$ source ./4-global_variables
CC=gcc
CDPATH=.:~:/usr/local:/usr:/
CFLAGS=-O2 -fomit-frame-pointer
COLORTERM=gnome-terminal
CXXFLAGS=-O2 -fomit-frame-pointer
DISPLAY=:0
DOMAIN=hq.garrels.be
e=
TOR=vi
FCEDIT=vi
FIGNORE=.o:~
G_BROKEN_FILENAMES=1
GDK_USE_XFT=1
GDMSESSION=Default
GNOME_DESKTOP_SESSION_ID=Default
GTK_RC_FILES=/etc/gtk/gtkrc:/nethome/franky/.gtkrc-1.2-gnome2
GWMCOLOR=darkgreen
GWMTERM=xterm
HISTFILESIZE=5000
history_control=ignoredups
HISTSIZE=2000
HOME=/nethome/franky
HOSTNAME=octarine.hq.garrels.be
INPUTRC=/etc/inputrc
IRCNAME=franky
JAVA_HOME=/usr/java/j2sdk1.4.0
LANG=en_US
LDFLAGS=-s
LD_LIBRARY_PATH=/usr/lib/mozilla:/usr/lib/mozilla/plugins
LESSCHARSET=latin1
LESS=-edfMQ
LESSOPEN=|/usr/bin/lesspipe.sh %s
LEX=flex
LOCAL_MACHINE=octarine
LOGNAME=franky
[...]
julien@ubuntu:/tmp/0x03$
- Local variables mandatory - 5-local_variables
Create a script that lists all local variables and environment variables, and functions.
julien@ubuntu:/tmp/0x03$ . ./5-local_variables
BASH=/bin/bash
BASHOPTS=checkwinsize:cmdhist:complete_fullquote:expand_aliases:extglob:extquote:force_fignore:histappend:interactive_comments:progcomp:promptvars:sourcepath
BASH_ALIASES=()
BASH_ARGC=()
BASH_ARGV=()
BASH_CMDS=()
BASH_COMPLETION_COMPAT_DIR=/etc/bash_completion.d
BASH_LINENO=()
BASH_REMATCH=()
BASH_SOURCE=()
BASH_VERSINFO=([0]="4" [1]="3" [2]="46" [3]="1" [4]="release" [5]="x86_64-pc-linux-gnu")
BASH_VERSION='4.3.46(1)-release'
CLUTTER_IM_MODULE=xim
COLUMNS=133
COMPIZ_CONFIG_PROFILE=ubuntu
COMP_WORDBREAKS=$' \t\n"\'><=;|&(:'
DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-Fg27Lr20bq
DEFAULTS_PATH=/usr/share/gconf/ubuntu.default.path
DESKTOP_SESSION=ubuntu
[...]
julien@ubuntu:/tmp/0x03$
- Local variable mandatory - 6-create_local_variable
Create a script that creates a new local variable.
- Name: BETTY
- Value: Holberton
- Global variable mandatory - 7-create_global_variable
Create a script that creates a new global variable.
- Name: HOLBERTON
- Value: Betty
- Every addition to true knowledge is an addition to human power mandatory - 8-true_knowledge
- Write a script that prints the result of the addition of 128 with the value stored in the environment variable TRUEKNOWLEDGE, followed by a new line.
julien@production-503e7013:~$ export TRUEKNOWLEDGE=1209
julien@production-503e7013:~$ ./8-true_knowledge | cat -e
1337$
julien@production-503e7013:~$
```
9. Divide and rule mandatory - [9-divide_and_rule](9-divide_and_rule/)
Write a script that prints the result of POWER divided by DIVIDE, followed by a new line.
- POWER and DIVIDE are environment variables
```
julien@production-503e7013:~$ export POWER=42784
julien@production-503e7013:~$ export DIVIDE=32
julien@production-503e7013:~$ ./9-divide_and_rule | cat -e
1337$
julien@production-503e7013:~$
```
10. Love is anterior to life, posterior to death, initial of creation, and the exponent of breath mandatory - [10-love_exponent_breath](10-love_exponent_breath/)
Write a script that displays the result of BREATH to the power LOVE
- BREATH and LOVE are environment variables
```
The script should display the result, followed by a new line
julien@production-503e7013:~/$ export BREATH=4
julien@production-503e7013:~/$ export LOVE=3
julien@production-503e7013:~/$ ./10-love_exponent_breath
64
julien@production-503e7013:~/$
```
11. There are 10 types of people in the world -- Those who understand binary, and those who don't mandatory - [11-binary_to_decimal](11-binary_to_decimal/)
Write a script that converts a number from base 2 to base 10.
- The number in base 2 is stored in the environment variable BINARY
- The script should display the number in base 10, followed by a new line
```
julien@production-503e7013:~/$ export BINARY=10100111001
julien@production-503e7013:~/$ ./11-binary_to_decimal
1337
julien@production-503e7013:~/$
```
12. Combination mandatory - [12-combinations](12-combinations//)
Create a script that prints all possible combinations of two letters, except oo.
- Letters are lower cases, from a to z
- One combination per line
- The output should be alpha ordered, starting with aa
- Do not print oo
- Your script file should contain maximum 64 characters
```
julien@ubuntu:/tmp/0x03$ echo $((26 ** 2 -1))
675
julien@ubuntu:/tmp/0x03$ ./12-combinations | wc -l
675
julien@ubuntu:/tmp/0x03$
julien@ubuntu:/tmp/0x03$ ./12-combinations | tail -303 | head -10
oi
oj
ok
ol
om
on
op
oq
or
os
julien@ubuntu:/tmp/0x03$
```
13. Floats mandatory - [13-print_float](13-print_float/)
Write a script that prints a number with two decimal places.
- The number will be stored in the environment variable NUM.
```
ubuntu@ip-172-31-63-244:~/0x03$ export NUM=0
ubuntu@ip-172-31-63-244:~/0x03$ ./13-print_float
0.00
ubuntu@ip-172-31-63-244:~/0x03$ export NUM=98
ubuntu@ip-172-31-63-244:~/0x03$ ./13-print_float
98.00
ubuntu@ip-172-31-63-244:~/0x03$ export NUM=3.14159265359
ubuntu@ip-172-31-63-244:~/0x03$ ./13-print_float
3.14
ubuntu@ip-172-31-63-244:~/0x03$
```
14. Decimal to Hexadecimal mandatory - [14-decimal_to_hexadecimal](14-decimal_to_hexadecimal/)
Write a script that converts a number from base 10 to base 16.
- The number in base 10 is stored in the environment variable DECIMAL
- The script should display the number in base 16, followed by a new line
```
julien@production-503e7013:~/$ export DECIMAL=16
julien@production-503e7013:~/$ ./14-decimal_to_hexadecimal
10
julien@production-503e7013:~/$ export DECIMAL=1337
julien@production-503e7013:~/$ ./14-decimal_to_hexadecimal | cat -e
539$
julien@production-503e7013:~/$ export DECIMAL=15
julien@production-503e7013:~/$ ./14-decimal_to_hexadecimal | cat -e
f$
julien@production-503e7013:~/$
```
15. What happens when you type ls *.c mandatory - [See Blog](https://www.linkedin.com/pulse/what-happens-when-you-type-ls-c-carlos-garcia)
Write a blog post describing step by step what happens when you type ls *.c and hit Enter in your shell. Try to explain every step you know of, and give examples. A total beginner should understand what you have written.
16. What is the difference between a hard link and a symbolic link? mandatory - [See Blog](https://www.linkedin.com/pulse/what-difference-between-hard-link-symbolic-carlos-garcia)
Write a blog post explaining what are hard and symbolic links on Linux, how to create them, and what is the difference between the two. Use examples to illustrate.
17. Everyone is a proponent of strong encryption #advanced - [100-rot13](100-rot13/)
Write a script that encodes and decodes text using the rot13 encryption. Assume ASCII.
```
julien@production-503e7013:~/shell/fun_with_the_shell$ cat quote
"Everyone is a proponent of strong encryption."
- Dorothy E. Denning
julien@production-503e7013:~/shell/fun_with_the_shell$ ./100-rot13 < quote
"Rirelbar vf n cebcbarag bs fgebat rapelcgvba."
- Qbebgul R. Qraavat
julien@production-503e7013:~/shell/fun_with_the_shell$
```
18. The eggs of the brood need to be an odd number #advanced - [101-odd](101-odd/)
Write a script that prints every other line from the input, starting with the first line.
```
ubuntu@ip-172-31-63-244:/$ \ls -1
bin
boot
dev
etc
home
initrd.img
lib
lib32
lib64
libx32
lost+found
media
mnt
opt
proc
root
run
sbin
srv
sys
t
#t#
t~
tmp
usr
var
vmlinuz
whoareyou
ubuntu@ip-172-31-63-244:/$ \ls -1 | ./101-odd
bin
dev
home
lib
lib64
lost+found
mnt
proc
run
srv
t
t~
usr
vmlinuz
ubuntu@ip-172-31-63-244:/$
```
19. I'm an instant star. Just add water and stir. #advanced - [102-water_and_stir](102-water_and_stir/)
Write a shell script that adds the two numbers stored in the environment variables WATER and STIR and prints the result.
- WATER is in base water
- STIR is in base stir.
- The result should be in base behlnort
```
julien@production-503e7013:~$ export WATER="ewwatratewa"
julien@production-503e7013:~$ export STIR="ti.itirtrtr"
julien@production-503e7013:~$ ./102-water_and_stir
holberton
julien@production-503e7013:~$
```