Linux File Compress commands

File Compress commands 

Linux we have two types of compress commands

  1. GZIP
  2. GUNZIP

To reduce the file size by using compress commands

gzip – This command used to compress the file size

[oracle@oracletest scripts]$ gzip ramkumar.txt
[oracle@oracletest scripts]$ ls -l
total 24
-rwxrwxrwx. 1 oracle oracle 72 Oct 21 01:49 ramkumar.txt.gz
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh

Gunzip – This command is user to unzip the original file size

[oracle@oracletest scripts]$ gunzip ramkumar.txt.gz
[oracle@oracletest scripts]$ ls -l
total 24
-rwxrwxrwx. 1 oracle oracle 42 Oct 21 01:49 ramkumar.txt
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh
[oracle@oracletest scripts]$

 

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Linux Link Commands

Linux Link Commands

Creating links is a kind of shortcut to access a file. Links allow more than one file name to refer to the same file.

There are two types of links :

  1. Hard Link
  2. Soft Link or Symbolic links

Hard Link

A hard link is one most power full links in the Linux system when we create a hard link to the file and then delete the file, we can still access the file using the hard link.

syntax : ln file_name link_name
Eg: ln ramkumar.txt ram

[oracle@oracletest scripts]$ ls -l
total 24
-rwxrwxrwx. 1 oracle oracle 42 Oct 21 01:49 ramkumar.txt
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh
[oracle@oracletest scripts]$ ln ramkumar.txt ram
[oracle@oracletest scripts]$ ls -l
total 28
-rwxrwxrwx. 2 oracle oracle 42 Oct 21 01:49 ram
-rwxrwxrwx. 2 oracle oracle 42 Oct 21 01:49 ramkumar.txt
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh
[oracle@oracletest scripts]$ cat ram
HI 
Hello
welcome to linux basic commands
[oracle@oracletest scripts]$ rm -rf ramkumar.txt
[oracle@oracletest scripts]$ ls -l
total 24
-rwxrwxrwx. 1 oracle oracle 42 Oct 21 01:49 ram
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh
[oracle@oracletest scripts]$ cat ram
HI 
Hello
welcome to linux basic commands


 

Soft Link or Symbolic links

Soft link is another variety type of Linux link, But if we create a soft link of the file and then delete the file, we can’t access the file through the soft link, and the soft link becomes dangling

Syntax: ln -s file_name link_name

Eg: ln -s ramkumar.txt ram

Eg: ls -s sample.txt kar

[oracle@oracletest scripts]$ ln -s sample.txt kar
[oracle@oracletest scripts]$ ls -l
total 28
lrwxrwxrwx. 1 oracle oracle 9 Oct 21 23:12 ram -> sample.txt
-rw-rw-r--. 1 oracle oracle 49 Oct 21 23:12 ramkumar.txt
-rwxrwxrwx. 1 oracle oracle 42 Oct 21 01:49 ram
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh
[oracle@oracletest scripts]$ cat ram
Good morning
How are you all
Take care
Bye Bye !
[oracle@oracletest scripts]$ rm -rf sample.txt
[oracle@oracletest scripts]$ ls -l
total 24
lrwxrwxrwx. 1 oracle oracle 9 Oct 21 23:12 ram -> sample.txt
-rwxrwxrwx. 1 oracle oracle 42 Oct 21 01:49 ram
-rwxrwxr-x. 1 oracle oracle 1291 Oct 20 23:47 rman_bkp.sh
-rw-rw-r--. 1 oracle oracle 6979 Oct 20 23:48 rman.log
-rwxr--r--. 1 oracle oinstall 515 Sep 9 14:45 setEnv.sh
-rwxr--r--. 1 oracle oinstall 134 Sep 7 10:54 stop_all.sh
[oracle@oracletest scripts]$ cat ram
cat: ram: No such file or directory

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Linux search commands

Linux search commands

In Linux, we have four various types of search commands

  • Grep

Grep is an acronym that stands for Global Regular Expression Print.

Grep is a Linux command used to search for a string of characters in a specified file.

To Search a File:

Syntax: Grep match_string file_name

Eg: grep database sample1

To Search Multiple Files: 

To search multiple files with the grep command, insert the filenames you want to search, separated with a space character.

Syntax: grep match_string file_name file_name

Eg: grep database sample1 sample2 sample3
  • AWK

AWK this command  is used for pattern search and processing, scanning files line by line then performing specified actions on matching lines

Syntax: awk ‘{search options from to}’ file_name

Eg: $ awk '{print $2 "\t" $3}' file.txt
  • Locate

locate command and find command is used to search a file by name. But, the difference between both commands is that locating command is a background process and searches the file in the database whereas, find command searches in the file system. The locate command is much faster than the find command.

We have some options in locating search commands by locate -h (help cmd)
Search for entries in a locate database.

-A, --all only print entries that match all patterns
-b, --basename match only the base name of path names
-c, --count only print number of found entries
-d, --database DBPATH use DBPATH instead of default database (which is
/var/lib/mlocate/mlocate.db)
-e, --existing only print entries for currently existing files
-L, --follow follow trailing symbolic links when checking file
existence (default)
-h, --help print this help
-i, --ignore-case ignore case distinctions when matching patterns
-l, --limit, -n LIMIT limit output (or counting) to LIMIT entries
-m, --mmap ignored, for backward compatibility
-P, --nofollow, -H don't follow trailing symbolic links when checking file
existence
-0, --null separate entries with NUL on output
-S, --statistics don't search for entries, print statistics about each
used database
-q, --quiet report no error messages about reading databases
-r, --regexp REGEXP search for basic regexp REGEXP instead of patterns
--regex patterns are extended regexps
-s, --stdio ignored, for backward compatibility
-V, --version print version information
-w, --wholename match whole path name (default)
Syntax: locate {Options…..} (filename)

 Eg:  locate ramkumar.txt

[oracle@oracletest pfile]$ locate ramkumar.txt
/home/oracle/scripts/ramkumar.txt

  • Find

find command is one of the most powerful tools in Linux, It supports searching by file, folder, name, creation date, modification date, owner, and permissions.

By using the ‘-exec’

Syntax: find [where to start searching from]
[expression determines what to find] [-options] [what to find]

Eg: find ramkumar

Options :

-exec CMD: The file being searched which meets the above criteria and returns 0 
for as its exit status for successful command execution.

-ok CMD : It works same as -exec except the user is prompted first.

-inum N : Search for files with inode number ‘N’.

-links N : Search for files with ‘N’ links.

-name demo : Search for files that are specified by ‘demo’.

-newer file : Search for files that were modified/created after ‘file’.

-perm octal : Search for the file if permission is ‘octal’.

-print : Display the path name of the files found by using the rest of the criteria.

-empty : Search for empty files and directories.

-size +N/-N : Search for files of ‘N’ blocks; ‘N’ followed by ‘c’can be used to 
measure size in characters; ‘+N’ means size > ‘N’ blocks and ‘-N’ means 
size < 'N' blocks.

-user name : Search for files owned by user name or ID ‘name’.

\(expr \) : True if ‘expr’ is true; used for grouping criteria combined with OR or AND.

! expr : True if ‘expr’ is false.

 

 

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Linux File Commands

Linux File Commands

File creating commands

Touch: This touch command is used to update the timestamps on existing files and as creating new files and empty files.

 

 

Vi: virtual editor vi filename.txt commands used to create a virtual editor

By pressing keys on the keyboard to perform an action in vi


Insert – a,I,o,u

  • :w! – Save the file but keep it open
  • :q! – Quit without saving:
  • :wq! – Save the file and quit

Cat: This cat command is mainly used to read files, But it can also be used to create new files.

 

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