The document provides a survival guide and cheat sheets for working efficiently in a Linux/UNIX environment while doing proof of concept or prototype work, covering topics such as working in the shell, storage and disk management using tools like LVM, text processing utilities, and configuration files that are important to understand. It also includes shortcuts for common tasks like adding a disk without restarting or creating an offline yum package repository for dependency resolution.

1. © 2014 IBM Corporation
IBMID Linux
POT/POC Survival Guide
Nugroho Gito
Software Client Architect
ngito@id.ibm.com

2. 2
Document Version
Version Date Author Description
0.1 2015-12-20 Nugroho Gito Initial Version
13 April 2017

3. 3
Agenda
1. Background
2. Pre Requisites
3. Working in Shell
1. UNIX Input/Output Streams
2. Environment variables
3. Regular Expression
4. Text Processing
5. VIM
6. Intro to Shell Scripting
4. Storage
1. Disk, Partition, File System Concept
2. Logical Volume Manager Concept
3. Disk, Partition Commands – Without LVM
4. Disk, Partition Commands – With LVM (GUI
& CLI)
5. Cheat Sheets
1. Global Configuration File
2. Adding disk without restart
3. Creating Offline yum Repository
4. Resolving Dependency Quickly with rpm
5. How to keep IP Address unchanged after
copying VM
6. Configure X Server
7. Passwordless ssh/sftp
8. Configure yum from IBM FTP
6. VMWare Networking
1. NAT
2. Bridge
3. Host-Only
7. VMWare Tools
1. Shared Folder
2. CD/DVD Emulation
8. VMWare vCenter Converter
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4. 4
1. Background
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5. 5
1. Background
 Basic survival guide and cheat sheets on Linux
 How to survive POC / POT
 Work efficiently in Linux/UNIX environment
 Most of the commands here can work in Linux/UNIX
 Most UNIX commercial distributions inherited from AT&T System V, therefore by default it
will not come with GNU based utilities.
Some commands can only work on GNU based utilities (eg: gawk, vim)
 Basic Text Processing in Linux/UNIX
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6. 6
2. Pre Requisites
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2. Pre Requisites
 This work for Red Hat based distributions including:
– Red Hat Enterprise Linux
– CentOS
– Fedora
 Linux ISO files
Having Linux ISO files proves to be very handy, so please get ISO files from:
https://ftp3.linux.ibm.com/
(Requires manager’s approval)
 How to know my Linux version?
cat /etc/redhat-release
 Hypervisor: VMWare Workstation
Get VMWare License from here:
https://nasoftware.ibm.com/sales/ctp.nsf/doc/MODM-7BQT8L?OpenDocument
(Requires manager’s approval)
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3. Working in Shell
Make friend with bash or ksh!
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3. Working in Shell
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 Most Linux distributions uses bash, however key navigation in bash is slightly different with
ksh (Korn Shell) which uses vi key binding
 The advantage of using vi key binding, it uses the same vi navigation key, and it provides
more advanced command line editing
 From this onward, we will turn on vi key binding by using following command:

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3. Working in Shell
set –o vi # We can put this in $HOME/.bashrc to automatically executed after user login
http://www.catonmat.net/download/bash-vi-editing-mode-cheat-sheet.pdf
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3.1. UNIX Input/Output Streams (IMPORTANT!)
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Standard Streams Pipeline Processing
I/O Redirections

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3.1. UNIX Input/Output Streams Sample
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Command Description
db2 << EOF 2>&1 > db2.out
get db cfg
get dbm cfg
list db directory
connect to LDAPDB2B
list tables
EOF
1. Execute db2 command
2. Redirect all input, delimited by string EOF
3. Redirect stderr (2) (2>&1) to stdout (1)
4. Redirect stdout to db2.out file
5. db2 command will execute all lines in red
find / -type f -ls | sort -rnk 7 | head -n 10 1. List all files from / directory
2. Sort output reverse order (highest to lowest)
based on column 7 (file size)
3. Limit output to 10 rows only
find / -name *.txt | xargs grep –i text
find / -name “*.txt” | xargs grep –i text
1. List all txt files from / directory
2. Find text ignore case in each txt files

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3.2. Shell Environment Variables (IMPORTANT!)
Variable Description
DISPLAY Contains the identifier for the display that X11 programs should use by default.
HOME Indicates the home directory of the current user: the default argument for the cd built-in command.
IFS Indicates the Internal Field Separator that is used by the parser for word splitting after expansion.
LANG
LANG expands to the default system locale; LC_ALL can be used to override this. For example, if its
value is pt_BR, then the language is set to (Brazilian) Portuguese and the locale to Brazil.
LD_LIBRARY_PATH
On many Unix systems with a dynamic linker, contains a colon-separated list of directories that the
dynamic linker should search for shared objects when building a process image after exec, before
searching in any other directories.
PATH
Indicates search path for commands. It is a colon-separated list of directories in which the shell looks for
commands.
PWD Indicates the current working directory as set by the cd command.
RANDOM Generates a random integer between 0 and 32,767 each time it is referenced.
SHLVL
Increments by one each time an instance of bash is started. This variable is useful for determining
whether the built-in exit command ends the current session.
TERM Refers to the display type
TZ Refers to Time zone. It can take values like GMT, AST, etc.
UID Expands to the numeric user ID of the current user, initialized at shell startup.
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http://www.tutorialspoint.com/unix/unix-environment.htm

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3.3. Regular Expression
 TODO
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3.4. Text Processing
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No Command Description Samples
1 cat concatenate files and print on the standard output
2 wc print newline, word, and byte counts for each file
3 grep print lines matching a pattern
4 head output the first part of files
5 tail output the last part of files
6 awk pattern scanning and processing language
7 sed stream editor for filtering and transforming text
8 tr translate or delete characters
9 cut remove sections from each line of files
10 paste merge lines of files
11 colrm remove columns from a file
12 expand convert tabs to spaces
13 unexpand convert spaces to tabs
14 diff compare files line by line
15 comm
16 cmp compare two files byte by byte
17 fold wrap each input line to fit in specified width
18 bc
19 split split a file into pieces
20 uniq report or omit repeated lines
21 sort sort lines of text files
22 join join lines of two files on a common field
http://www.ibm.com/developerworks/aix/library/au-unixtext/
http://www.ibm.com/developerworks/aix/library/au-textprocess.html

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3.5. VIM
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3.6. Intro to Shell Scripting
 Looping (for)
for file in `ls /etc/`; do
echo $file
done
 Looping (while)
ls /etc/ | while read file; do
echo $file
done
 Math expression
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4. Storage
Disk, Partition, File System & LVM
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4.1. Disk, Partition, File System Concept
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4.2. Disk, Partition Commands – Without LVM
fdisk /dev/sdb # create new partition: press n (new
# partition), accept all default settings
# to create partition on all usable disk,
# press w (write partition)
mkfs.ext4 /dev/sdb1 # format new partition
blkid /dev/sdb1 # write down new partition uuid (optional)
vi /etc/fstab # Add new entry to /etc/fstab
mount /opt # mount partition, make it readable/writable to OS
df -h # new partition should appear
ls -la /dev/disk/by-uuid # to see all UUID for each partition (optional)
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4.3. Logical Volume Manager - Concept
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User Interface Command
CLI lvm
GUI system-config-lvm

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4.3. Disk, Partition Commands – With LVM (CLI)
Scenario:
1. Create new volume group (vgtest) from two unformatted disk (sdd & sde)
2. Create new logical volume
3. Format newly created logical volume
4. Mount logical volume
(root)/root>fdisk -l
Disk /dev/sda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 1305 10377990 8e Linux LVM
Disk /dev/sdb: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 652 5237158+ 83 Linux
Disk /dev/sdc: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 1 652 5237158+ 83 Linux
Disk /dev/sdd: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdd doesn't contain a valid partition table
Disk /dev/sde: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sde doesn't contain a valid partition table
(root)/root>pvcreate /dev/sdd
Physical volume "/dev/sdd" successfully created
(root)/root>pvcreate /dev/sde
Physical volume "/dev/sde" successfully created
(root)/root>vgcreate vgtest /dev/sdd /dev/sde
/dev/hdc: open failed: No medium found
Volume group "vgtest" successfully created
(root)/root>lvcreate -L 500M -n lvol0 vgtest
/dev/hdc: open failed: No medium found
Logical volume "lvol0" created
(root)/root>mkfs -t ext3 -m 1 -v /dev/vgtest/lvol0
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
128016 inodes, 512000 blocks
5120 blocks (1.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67633152
63 block groups
8192 blocks per group, 8192 fragments per group
2032 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 33 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
(root)/root>mkdir /mnt/vfs
(root)/root>mount -t ext3 /dev/vgtest/lvol0 /mnt/vfs
(root)/root>cd /mnt/vfs
(root)/mnt/vfs>df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vgtest-lvol0
485M 11M 469M 3% /mnt/vfs
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4.4. Disk, Partition Commands – With LVM (GUI)
Scenario:
1. Make sure X Window Manager already installed
2. Run system-config-lvm
3. Initialize Entries
4. Create Volume Group
5. Add Physical Volume
6. Create Logical Volume, set LV Size, File System & Mount Point
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5. Cheat Sheets
Shortcuts that can save you hours of manual work
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5.1. Global Configuration File (IMPORTANT!)
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No File Name Description
1 /etc/bashrc Global BASH startup scripts
2 /etc/profile Global environment variable
3 /etc/inittab Controls how Linux start (3:text mode multi user, 5:X11)
4 /etc/fstab Controls which file system automatically mounted during startup
5 /etc/kde/kdm/kdmrc Controls how KDE start X server
6 /etc/gdm/custom.cnf Controls how GNOME starts X server, to enable X listening to TCP port, add
DisallowTCP=false under [security]
7 /etc/profile.d/ Global application environment setup
8 /etc/network/interfaces List of network interfaces
9 /etc/xinetd.conf Replacement of UNIX inetd.conf which refers to files unde /etc/xinetd.d
10 /etc/hosts.allow Lists of allowed host (tcp wrapper)
11 /etc/hosts.deny Lists of denied host (tcp wrapper)
12 /etc/redhat-release Release version
13 /etc/sysctl.conf Kernel settings
14 /etc/security/limits.conf Shell limits per user
15 /etc/udev/rules.d/70-persistent-net.rules Mapping between MAC address with ethernet devices (ethX)
16 /etc/sysconfig/network-scripts/ifcfg-ethX IP Address/Network Mask/Gateway settings
17 /etc/resolv.conf DNS Settings (DHCP)
18 /etc/selinux/config SE Linux config
19 /etc/hosts Host Name mapping between IP Address to Host Name or FQDN
20 /proc/meminfo Memory info, MemTotal & SwapTotal
21 /proc/cpuinfo Processor info, MemTotal & SwapTotal
Background
• Sometimes config require changes but have no clue where its location?

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5.2. Adding Disk without Restart
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Background
• Running out of disk while installing some software? Follow this command to quickly expand
your file system
# How to add new disk to RHEL, and force to rescan without reboot
for i in `ls /sys/class/scsi_host`; do
echo "- - -" > /sys/class/scsi_host/$i/scan
fdisk -l
tail -f /var/log/message
done
# The rest of command includes creating new file system / increase
# existing file system

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Background
• When installing some software, it requires dependency to Linux package, and installing
with rpm will drive you crazy? Use offline yum repo, to install Linux package with yum with
auto dependency resolution.
# Steps
# 1. Insert 1st DVD into DVD ROM
# 2. Assuming CD/DVD ROM mount point is at /mnt/cdrom
# Manually configuring CD/DVD mount
# Modify /etc/fstab, add this:
# /dev/cdrom /mnt/cdrom iso9660 ro,user,noauto,unhide
# mkdir /mnt/cdrom
# mount /mnt/cdrom
# vi /etc/yum.repos.d/local.repo
# Add the following details.
[LocalRepo]
name=Local Repository
baseurl=file:///mnt/cdrom
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
yum clean all
5.3. Creating Offline yum Repository
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5.4. Resolving Dependency Quickly with rpm
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Background
• TODO

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5.5. How to keep IP Address unchanged after copying VM
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Background
• After copying VM and after boot you got this message "device eth0 does not seem to be
present, delaying initialization“, and VM can’t get any IP Address/IP Address got changed.
• Edit: /etc/udev/rules.d/70-persistent-net.rules
# This file was automatically generated by the /lib/udev/write_net_rules
# program, run by the persistent-net-generator.rules rules file.
#
# You can modify it, as long as you keep each rule on a single
# line, and change only the value of the NAME= key.
# PCI device 0x15ad:0x07b0 (vmxnet3) (custom name provided by external tool)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:50:56:bc:00:45", ATTR{type}=="1",
KERNEL=="eth*", NAME="eth0"
# PCI device 0x15ad:0x07b0 (vmxnet3)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:50:56:bc:00:46", ATTR{type}=="1",
KERNEL=="eth*", NAME="eth1"
• Delete the first SUBSYSTEM entry in the file.
• Update the 'eth1' attribute in the remaining entry to 'eth0'
• Edit /etc/sysconfig/network-scripts/ifcfg-eth0
• Change the HWADDR to match the new mac address listed in the newly edited 70-
persistent-net.rules file.
• reboot.

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Background
• Sometimes you need to kick off GUI program running on Linux/UNIX Host
• If you don’t have physical access to Host Console, and only remote access is available
(telnet/ssh)
5.6. Configure X Server
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5.7. Passwordless ssh/sftp
Background
Sometimes you frequently login to a server and you want to run unattended script from
remote.
Steps
1. ssh-copy-id user@host # It will prompt your password at remote host
2. ssh user@host # It won’t ask for password
3. sftp user@host # It won’t ask for password
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5.8. Configure yum from IBM FTP
Background
RHEL yum will not work without registered RHEL accounts. For IBMers this steps will
configure yum to work with IBM FTP.
Steps
wget -qO- --no-check-certificate https://rhn.linux.ibm.com/pub/bootstrap/bootstrap.sh | /bin/bash
rhnreg_ks --force --username=user@<cc>.ibm.com --password=your_ftp3_passwd
or
rhn_register
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