Useful UNIX Commands and Shell Scripts []

Moved to the page http://3rdstage.wikia.com/wiki/On_UNIX_and_Linux in my wiki as of 6th Jan. 2014.

Often-used Solaris Commands

Really concise and useful

http://www.themis.com/supp/suppfaqs/faqs_solaris.htm#q36

Identifying System Configuration

IBM AIX

• prtconf Command : displays system configuration information.

View files in octal or hexadecimal format - od

You can view non ascii base files in hexadecimal format using od command.

% od -A d -x journal.log

For more about od, refer the following.

• http://www.opengroup.org/onlinepubs/9699919799/utilities/od.html
• http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds4/od.htm

Find files with specified name and list them with full path

If you want to find files with extension of 'jar' and print them with full path, use find command with -exec operator like the following.

% find . -name '*.jar' -exec ls -l {} \;

For more about find command and -exec operator including strange '{}' or '\;' in the above example, refer the followings.

• http://www.opengroup.org/onlinepubs/9699919799/utilities/find.html
• http://docstore.mik.ua/orelly/unix3/upt/ch09_01.htm

Find files containing the specified word

List files using find command excluding files with 'Permission denined'

When executing find command in simplest format, you may get lots of lines just saying that 'Permission denied'. Most cases, those are not what you want, and lots of permission denied lines can disturb you identifying the wanted result.

You can use stderr redirection to cut out permission denied files (or directories).

• How can I exclude all “permission denied”-messages from “find .”? (from stackoverflow)
• Redirection on Wikipedia

Sorting the file system usage result from the du command

You can sort the output of du command applying pipe to sort command.

% du -m | sort -n

For more about du and sort, read the followings.

• du - estimate file space usage
• sort - sort, merge, or sequence check text files

Finding large files

To find large files(not directories) under current directory and list them in pages, use the following command.

% find . -type f -exec du -k {} 2>/dev/null \; | sort -nr | more

To filter out small files, you can use size option with find command, or to filter out some subdirectories you can redirect the result to grep command.
The following command will list files whose size are more than 1 mega-byte under current directory recursively except the subdirectories starting with 'svn' in order of their size.

% find . -type f -size +1000000c -exec du -k {} 2>/dev/null \; | sort -nr | grep -E "\./svn.*" -v

Identifying the shell of your current login

To identify what shell a user is set to use by default, you can check 'SHELL' variable.

As the above example shows, SHELL variable contains the login default shell type not the one currently in use.

Identifying the product of Linux installed

For Linux, /etc/issues file contains more detailed information on what Linux product it is.

Identifying TCP/IP ports currently in use.

You can identify TCP/IP ports currently in use using netstat command. The options of netstat is slightly different among operating systems.

For UNIX,

For Linux, You need root privilege to take effect of -p option

For Windows,

For more about netstat, refer topics in Wikipedia.

Inverse matching with grep command

To find lines not matching the specified patterns in a file, you can use -v option with grep command.

You don't need to be bothered to find out how to use complex negative patterns with regex.