Bash

Documentation

• Advanced Bash-Scripting Guide
• http://www.ss64.com/bash/index.html
• http://tille.xalasys.com/training/bash

Shell

Listing directory content:

ls --full-time               # To list files full date & time
ls -d directory-name         # List directory entries, not content
                             #  eg. ls -d /etc/rc*
ls -lS | head                # List biggest files first - print only first 10 entries
ls -lt | head -n 20          # List most recent files first, print only 20 first entries

Script Quick Tutorial

Environment

export MYVAR=myvalue && command-to-execute         #MYVAR defined for the current shell and invoked shell
MYVAR=myvalue && command-to-execute                #MYVAR defined for the current shell
MYVAR=myvalue command-to-execute                   #MYVAR only defined for the subsequent command

Loops

# On several lines
for f in $(seq 33296 33330); do
  wget "http://i.techrepublic.com.com/gallery/${f}.jpg"
done

# On a single line
for i in `seq 278 328`; do wget http://i.techrepublic.com.com/gallery/33$i.jpg; done

Interactivity

Read User's password

Reading input from user is done with the commands read. To prevent password echo on display, one can use the command stty:

###### Preventing echo with stty ######
read -p "Username: " uname
stty -echo
read -p "Password: " passw; echo
stty echo

Preventing password echo using option -s:

###### Using -s ######
PASS="abc123"
read -s -p "Password: " mypassword
echo ""
[ "$mypassword" == "$PASS" ] && echo "Password accepted" || echo "Access denied"

Complete solution:

###### Complete solution ######
USER=wbi\\titeuf
echo "Mounting windows share... Please type password for user $USER..."
# time-out after 60sec, raw input no escaping, no echo, prompt
read -t 60 -r -s -p "Password: " PASSWORD
# delete prompt line
echo -e -n "\r"
mount -t smbfs -o username="$USER",password="$PASSWORD",iocharset=iso8859-1,codepage=cp437 //windows-host/C$ /mnt/c
mount -t smbfs -o username="$USER",password="$PASSWORD",iocharset=iso8859-1,codepage=cp437 //windows-host/D$ /mnt/d
mount -t smbfs -o username="$USER",password="$PASSWORD",iocharset=iso8859-1,codepage=cp437 //windows-host/F$ /mnt/f
# delete password variable
PASSWORD=------------------------------------
PASSWORD=abcdefghijklmnopqrstuvwxyz0123456789
PASSWORD=------------------------------------

Miscellaneous

Execute the output of a process

eval 'dircolors'