System commands

System commands

Disk usage

df     report file system disk space blocks usage
df -i  disk space inodes usage
du    disk usage actual filesize
rm    remove file
mkdir  create directory
rmdir  remove empty directory

Process commands

ps        current processes
pmap  PID   memory map of process
kill  PID       kill process
kill  -TERM          default if no signal given (TERM=15)
pstree                     process tree
free        memory usage
ipcs        interprocess communication protocol
top         displays linux current tasks

Bash colours

Normal Colours
echo -e "\e[0;30m" Black
echo -e "\e[0;31m" Red
echo -e "\e[0;32m" Green
echo -e "\e[0;33m" Yellow
echo -e "\e[0;34m" Blue
echo -e "\e[0;35m" Purple
echo -e "\e[0;36m" Cyan
echo -e "\e[0;37m" White


Bold Colours

echo -e "\e[1;30m" Black
echo -e "\e[1;31m" Red
echo -e "\e[1;32m" Green
echo -e "\e[1;33m" Yellow
echo -e "\e[1;34m" Blue
echo -e "\e[1;35m" Purple
echo -e "\e[1;36m" Cyan
echo -e "\e[1;37m" White


Coloured with underline
echo -e "\e[4;30m"
echo -e "\e[4;31m"
echo -e "\e[4;32m" Green
echo -e "\e[4;33m"
echo -e "\e[4;34m" Blue
echo -e "\e[4;35m" Purple
echo -e "\e[4;36m" Cyan
echo -e "\e[4;37m" White

Background Colours
echo -e "\e[40m" Black
echo -e "\e[41m" Red
echo -e "\e[42m" Green
echo -e "\e[43m" Yellow
echo -e "\e[44m" Blue
echo -e "\e[45m" Purple
echo -e "\e[46m" Cyan
echo -e "\e[47m" White


Reset as of terminal colours
echo -e "\e[0m" Reset Text

The use of m indicates end of the codes

you can try out for combination
echo -e "\e[1;31m"Bold Red"\e[4;33m"Bold Yellow Underlined"\e[0;45m"Purple Background"\e[0m"

convert dos file to linux file

We often use the commands to convert the dos file to linux, using the commands

dos2unix - DOS/MAC to UNIX text file format converter
unix2dos - UNIX to DOS text file format converter

The conversion can be done by the commands tr and sed.

$ tr -d \\r < dos-file.txt > temp.txt && mv temp.txt dos-file.txt

here dos-file.txt will be converted to unix fileformat, temp.txt is the temporary file created and then renamed to dos-file.txt

$ sed -e 's/$/\r/g' unix-file.txt > temp.txt  && mv temp.txt unix-file.txt
here unix-file.txt will be converted to dos fileformat, temp.txt is the temporary file created and then renamed to unix-file.txt.

find: files between dates

Finding the files in the date range

check man find for more

 find - search for files in a directory hierarchy
        -mmin n
              File's data was last modified n minutes ago.
       -mtime n
              File's  data  was  last modified n*24 hours ago. 
       -type c
              File is of type c:
              b      block (buffered) special
              c      character (unbuffered) special
              d      directory
              p      named pipe (FIFO)
              f      regular file
              l      symbolic link; this is never true if the -L option or the -follow  option
                     is  in effect, unless the symbolic link is broken.  If you want to search
                     for symbolic links when -L is in effect, use -xtype.
              s      socket
              D      door (Solaris)

       -name pattern
              Base of file name (the path with the leading directories removed) matches  shell
              pattern  pattern.   The  metacharacters  (`*', `?', and `[]') match a `.' at the
              start of the base name (this is a change in findutils-4.2.2; see  section  STAN‐
              DARDS  CONFORMANCE  below).   To  ignore a directory and the files under it, use
              -prune; see an example in the description of -path.  Braces are  not  recognised
              as  being special, despite the fact that some shells including Bash imbue braces
              with a special meaning in shell patterns.  The filename  matching  is  performed
              with  the  use of the fnmatch(3) library function.   Don't forget to enclose the
              pattern in quotes in order to protect it from expansion by the shell.

---

Listing the files with date

$ ls -l

-rw-r----- 1 syslog adm 1555 2010-06-03 07:54 messages
-rw-r----- 1 syslog adm 487017 2010-05-30 08:02 messages.1
-rw-r----- 1 syslog adm 646 2010-05-23 07:59 messages.2.gz
-rw-r----- 1 syslog adm 415 2010-05-16 07:47 messages.3.gz
-rw-r----- 1 syslog adm 55321 2010-05-09 07:49 messages.4.gz

---

-mtime 4 gives the file created exactly 4 days ago (4*24)

$ find . -mtime 4

./messages.1

$ date -d "4 days ago"

Sun May 30 16:15:14 IST 2010

---

-mtime 11 gives the file created exactly 11 days ago (11*24)

$ find . -mtime 11

./messages.2.gz

$ date -d "11 days ago"

Sun May 23 16:16:04 IST 2010

---

-mtime -11 gives the files created from now till 11 days

$ find . -mtime -11

./messages
./messages.1

---

-mtime +11 gives files created after the 11th day

$ find . -mtime +11

./messages.3.gz
./messages.4.gz

---

now when we want the files created from 11th day and older or rather above ten days then we can have

$ find .  -mtime +10

./messages.2.gz
./messages.3.gz
./messages.4.gz

---

if we want to have list of files created 10 days before whose name begins with messages

$find . -mtime +10 -a -name "messages*" -a -type f -exec ls -l {} \;

-rw-r----- 1 syslog adm 646 2010-05-23 07:59 ./messages.2.gz
-rw-r----- 1 syslog adm 415 2010-05-16 07:47 ./messages.3.gz
-rw-r----- 1 syslog adm 55321 2010-05-09 07:49 ./messages.4.gz

I would always suggest to have the -a -type f option so you are surely working on files only, as ls -l will in sub-directories.

sed: for the text between matching pattern

sed -ne '/IC/,/EI/p' country-codes.txt where IC is the first pattern and IE is the last for the file having country codes

file:country-codes.txt
GY,Guyana
HA,Haiti
HO,Honduras
HU,Hungary
IC,Iceland
IN,India
ID,Indonesia
IR,Iran
IZ,Iraq
EI,Ireland
IM,Isle of Man
IS,Israel
IT,Italy

command: sed -ne '/IC/,/EI/p' country-codes.txt
IC,Iceland
IN,India
ID,Indonesia
IR,Iran
IZ,Iraq
EI,Ireland

ls --color Decorating Directory Listing

The change the colours for your directory listing
Edit file: /etc/DIR_COLORS, copy the only changed ones in ~/.dircolors.

Next login, you get it.

file: /etc/DIR_COLORS
# 00=none 01=bold 04=underscore 05=blink 07=reverse 08=concealed
# Text color codes:
# 30=black 31=red 32=green 33=yellow 34=blue 35=magenta 36=cyan 37=white
# Background color codes:
# 40=black 41=red 42=green 43=yellow 44=blue 45=magenta 46=cyan 47=white
#NORMAL 00 # no color code at all
#FILE 00 # normal file, use no color at all
RESET 0 # reset to "normal" color
DIR 01;34 # directory
LINK 01;36 # symbolic link (If you set this to 'target' instead of a
# numerical value, the color is as for the file pointed to.)

FTP GET remote file timestamp

Check the remote server file time
login to ftp server
ftp servername
do
ls -ltr

will show list of files say we have
ftp> ls -ltr

227 Entering Passive Mode (10,146,172,50,66,132)
150 Here comes the directory listing.
-rw-r--r-- 1 50005 50005 5250 Mar 01 08:15 tech-talk
226 Directory send OK.


use modtime filename to check the file modified timestamp, ftp always shows in GMT time

ftp> modtime tech-talk

tech-talk 03/01/2010 08:15:00 GMT