Common unix commands and utilities | unix commands and utilities Guide


To find a program not on this list (and there are hundreds), try the man program with the -k option followed by a keyword, for example,
man -k tape
to find all on-line manual entries that refer to programs that work with tapes.

Terminal control characters for C-shell (csh)

^h, backspace erase previously typed character
^u erase entire line of input so far typed
^d end-of-input for programs reading from terminal
^s suspend writing to terminal (freezes terminal)
^q continue writing to terminal
^z suspend currently running job; restart with bg or fg
^c kill currently running program and allow clean-up before exiting
^\ emergency kill of currently running program with no chance of cleanup

Also see a list of special characters that should not be used in filenames.

Login and authentication

login access computer; start interactive session
logout disconnect terminal session
passwd change local login password; you must set a strong password that is not easily guessed
kinit obtain kerberos ticket for connections to other kerberized computers
kdestroy destroy kerberos tickets (authorizations)


date show date and time
history list of previously executed commands
man show online documentation by program name
info online documentation for GNU programs
w, who who is on the system and what they are doing
whoami who is logged onto this terminal
top show system stats and top CPU using processes
uptime show one line summary of system status

File management

cat combine files
cp copy files
ls list files in a directory and their attributes
mv change file name or directory location
rm remove files
ln create another link (name) to a file
chmod set file permissions
crypt encode/decode a file with a private key
gzip, gunzip compress/decompress a file
find find files that match specific criteria

Display contents of files

cat copy files to display device
more show text file on display terminal with paging control
head show first few lines of a file(s)
tail show last few lines of a file; or reverse line order
vi full-featured screen editor for modifying text files
pico simple screen editor for modifying text files
grep display lines that match a pattern
lpr send file to printer
pr format file with page headers, multiple columns, etc.
diff compare two files and show differences
cmp compare two binary files and report if different
comm compare two files; show common or unique lines
od display binary files as eqivalent octal/hex codes
strings show printable text embedded in binary files
file examine file(s) and guess type: text, data, program, etc.
wc count characters, words, and lines in a file


cd change to new directory
mkdir create new directory
rmdir remove empty directory (you must remove files first)
mv change name of directory
pwd show current directory


df summarize free space on disk filesystems
du show disk space used by files or directories

Special character handling for C-shell (See man csh)

* match any characters in a file name
~user shorthand for home directory of user
$name substitute value of variable name
\ turn off special meaning of character that follows
in pairs, quote string with special chars, except !
in pairs, quote string with special chars, except !, $
` in pairs, substitute output from enclosed command

Controlling program execution for C-shell (See man csh)

& run job in background
^c kill job in foreground
^z suspend job in foreground
fg restart suspended job in foreground
bg run suspended job in background
; delimit commands on same line
() group commands on same line
! re-run earlier commands from history list
jobs list current jobs
ps show process information
kill kill background job or previous process
nice run program at lower priority
at run program at a later time
crontab run program at specified intervals
limit see or set resource limits for programs
alias create alias name for program (normally used in .login file)
sh, csh execute command file

Controlling program input/output for C-shell (See man csh)

| pipe output to input
> redirect output to a storage file
< redirect input from a storage file
>> append redirected output to a storage file
tee copy input to both file and next program in pipe
script make file record of all terminal activity

Email and communication

msgs read system bulletin board messages
mailx send/read email; can be run by other programs to send exisiting files via email
encode/decode a binary file for transmission via email
rn read USENET news groups

Editors and formatting utilities

sed programmable text editor for data streams
vi full-featured editor for character terminals
emacs GNU emacs editor for character terminals
xemacs GNU emacs editor for X Window terminals
pico very simple text editor
fmt fill and break lines to make all same length
fold break long lines to specified length

X Window client programs (output to X terminal or server)

xterm provide login shell window
xauth manipulate authorization files
xload show system load
xman full screen online manual viewer
xemacs GNU emacs editor
gv interface to contol gs to display PostScript or PDF files on screen
xdvi display DVI files on X Window (screen preview)
gnuplot interactive data plotting on screen

TeX typesetting system

tex process TeX files to DVI (device independent) output
latex process LaTeX files to DVI
dvips print DVI files on Postscript laser printer
xdvi display DVI files on X Window (screen preview)
latex2html translate LaTeX files to HTML (for web pages)

Printing (BSD based)

lpr send file to print queue
lpq examine status of files in print queue
lprm remove a file from print queue
enscript convert text files to PostScript format for printing

Interpreted languages and data manipulation utilities

sed programmable text editor for data streams
awk pattern scanning and processing language
perl Practical Extraction and Report Language
sort sort or merge lines in a file(s) by specified fields
tr translate characters
cut cut out columns from a file
paste paste columns into a file
dd copy data between devices; reblock; convert EBCDIC

Graphics and mapping

gnuplot interactive data plotting; outputs to PostScript or X Window
gs “ghostscript” converter displays PostScript files on X Window displays or other devices


ssh remote login/command execution; encrypted
scp remote non-interactive file copy; encrypted
sftp remote interactive file copy; encrypted
telnet remote network login; plain text password – not recommended
ftp network file transfer program; plain text password – not recommended
host find IP address for given host name, or vice versa
lynx web browser for character based (text-only) terminals
gzip, gunzip compress/decompress a file
tar combine multiple files/dirs into single archive
encode/decode a binary file for transmission via email

Compilers, interpreters and programming tools

csh command language interpreter (C-shell scripts)
ksh command language interpreter (Korn-shell scripts)
sh command language interpreter (Borne-shell scripts)
f77 Fortran 77 compiler
f2c convert fortran source code to C source code
gcc GNU C compiler
g++ GNU C++ compiler
dbx command-line symbolic debugger for compiled C or Fortran
make recompile programs from modified source
cflow generate C flow graph

Programming libraries (see man library_name)

lapack Fortran 77 routines for numerical linear algebra (supersedes LINPACK and EISPACK)
X routines to interface with X window system (no man page — get the X Toolkit book)
dbm database routines
xdr library routines for external data representation
netcdf routines for machine independent data representation

Tape manipulation and archiving

mt manipulate tape drive and position tape
dd unformatted tape read and write; file conversion
tar archive disk files on tape or disk
ltf read/write ANSI standard label tapes
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General SCM Interview Questions – SCM Job Interview Kit



General SCM Interview Questions – SCM Job Interview Kit

  • What do you think about configuration management?
  • What do you understand about Change Management?
  • branching methodologies and what currently theya re using it. Show with some example with pros and cons
  • Concept of Merging and Why do we need?
  • What do you think about build Management?
  • What are the key benefit of build Automation and what are the key inputs to automate the build process in the project?
  • Discuss about tools and technology which help to automate the entire build cycle.
  • What is Continuous Build Integration and How this is useful for the project?
  • What is daily build & nightly builds and what are the process need to set up to Automate & monitor consistently.
  • Explain in details for writing build sciprt for any project
  • What do you think about release Management?
  • Talk about Release Management on several platforms?
  • What do you understand about Packaging and Deployment?
  • How to Automate Remote Deployment of Builds on Development & Test Servers?
  • What is workflow management. exmplain this in details.
  • What do you understand about Code Coverage? Describe repective tools & utilities.
  • Describe the Integrate Packaging scripts & Test Automation scripts with build & Monitor build verification test status and tools.
  • How to co-ordinate with development team to increase their productiavity.
  • What do you understand about multisite project
  • How SCM team perform integration and co-ordination between Dev and QA
  • Explain Troubleshooting in Build Server and Process
  • Explain Troubleshooting in Configuration Server and Process
  • Explain Troubleshooting inMost popular java Comipler issues in build server
  • Explain Troubleshooting inMost popular C++ compiler issues in build server
  • software packaging tools if they will be packaging or writing the installations for the releases.
  • Backup your code daily with respect to SVN.
  • Overview of Batch Scripts and top 25 commands
  • Discuss about Web Servers and Application servers
  • What do you think about distributed and multi-site environment
  • Can you name some software development methodologies and describe them?
  • Agile attempts to minimize risk by developing software in short iterations.
  • Extreme Programming employs simplicity, frequent communication, constant customer feedback and decision empowerment.
  • Iterative development is a cyclical methodology that incorporates refactorying into the process.
  • Waterfall software development is a phased methodology. When one phase is complete, it moves onto the next phase.
  • What is an API?
  • What is a web service?
  • What the difference between a global and a local variable?
  • What are Bug /Issue Tatcking tools available and descibe them
  • How does Subversion handle binary files?
  • What is ADO?
  • What is polymorphism?
  • Plz Let me the Difference Between Bea Weblogic IBM Websphere


  • What are basic skills required for Perforce administration including Command Line info.
  • How we can develop Build summary reports for Mgmt team and what are the key inputs for report.
  • Explain the best practice for Setup process & maintain the Archive of software releases (internal & external) & license management of Third Party Libraries
  • Identify the Cdeployment tools for major/minor/patch releases in different environment.
  • Explain Red Hat Linux and some of daily used features.
  • Explain Perforce & Multisite
  • Concept of labeling, branching and merging
  • labeling, branching and merging in perforce

Talk about Release Process

Can you describe some source code control best practice?
# Use a reliable and dedicated server to house your code.
# Backup your code daily.
# Test your backup and restore processes.
# Choose a source control tool that fits your organization’s requirements.
# Perform all tool specific administrative tasks.
# Keep your code repositories as clean as possible.
# Secure access to your code.

Can you describe software build best practices?
# Fully automated build process
# Build repeatability
# Build reproducibility
# Build process adherence

CM tools Comparison

  • Difference Between CVS and SVN
  • Difference Between perforce and SVN
  • Difference Between perforce and Clearcasee
  • Difference Between VSS and TFSC
  • Difference Between perforce and MKS



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List of 5 Common Problems in CVS – Troubleshooting Guide


List of 5 Common Problems in CVS – Troubleshooting Guide

  • Problem 1:- How will we modify our conflict occurred files ?

While updating if you will get message like bellow, then check,

This will list:

* “A filename” for files that you added
* “M filename” for files that you modified
* “C filename” for files that have conflicts

Conflicts are files that you modified and that were modified on the head revision as well.

@ If u ll get C or conflict then go to that file and remove that lines and duplicate line then it will recover, it because, if more than two developer working on same file and comming on same time then conflict occures,

Files with conflicts will have conflict markers in them. Conflict markers look like:

<<<<<<< filename
your lines
other person’s lines
>>>>>>> current version

  • Problem 2:-

If you are using your colleague’s checked out code for some changes, after that If you made any changes in code and then if you will try to check-in the code in CVS from your machine,after that if  it will ask your colleague’s password for checking-in. So How will we resolve this one ?

Please fine the CVS dir on your present code directory, then go to CVS dirctory, there, you will find Entries, Root, Repository like files , So now open that Rot file and change that username then your problem will solve, else let me know.
cd CVS
vim Root
edit present urername to your username
:wq   // save and quit
cd ..  // come to parent directory
then do your work ..
it will fine

  • Problem 3:-
    Is there any way to identify the information of deleted lines in a file through CVS annotate or any other means?


         You deleted from CVS or local server ? if u deleted from both server then i have to see, else if u deleted from      either local server or CVS server  then do “cvs -q up -Pd  “

else do cvs -q up -Pd -r  ” .

  •  Problem4:-

           When I view the “cvs log”, the log report is fetching the file but says

            “date: 2008/12/31 06:00:51;  author: amareshcd;  state: Exp;  lines: +0 -0”
But I have added with 130 lines. Why the log is not showing “+130 -0” in its report.   ?


Use ,“cvs log -d date1 logfile.log”

  •  Problem5:-

        I have files that went into the Attic.  How do I restore them back? Viewing  the files  revealed that they’re in DEAD State. Someone has ‘cvs remove’d the files. Just restore them with ‘cvs add’. How ?


cvs log
Find til newest non-dead version
step 3:-
cvs update -r
mv foo
step 5:-
cvs update -A
step 6:-
mv foo
step 7:-
cvs add
step 8:-
cvs commit -m “bring out your dead”

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