Miscellaneous Linux Commands

Find All Files Containing Specific Text On Linux

Do the following:

grep -rnw '/path/to/somewhere/' -e 'pattern'

• -r or -R is recursive,
• -n is line number, and
• -w stands for match the whole word.
• -l (lower-case L) can be added to just give the file name of matching files.

Along with these, --exclude, --include, --exclude-dir or --include-dir flags could be used for efficient searching:

• This will only search through those files which have .c or .h extensions:
  

  grep --include=\*.{c,h} -rnw '/path/to/somewhere/' -e "pattern"
  

• This will exclude searching all the files ending with .o extension:

grep --exclude=*.o -rnw '/path/to/somewhere/' -e "pattern"

• Just like exclude files, it's possible to exclude/include directories through --exclude-dir and --include-dir parameter. For example, this will exclude the dirs dir1/, dir2/ and all of them matching *.dst/:

grep --exclude-dir={dir1,dir2,*.dst} -rnw '/path/to/somewhere/' -e "pattern"

This works very well for me, to achieve almost the same purpose like yours.

View List of Files in ZIP archive on Linux

• unzip -l zipfilename ( where l is for list )
• less zipfilename

Read Contents of Zipped Files without 

1. first use -l to list
2. Then 'unzip -c archive.zip file1.txt file2.txt | less'

Must pipe to less else the contents fly by , without you being able to see it.


Replacing a File inside an archive

1. extract file : jar -xf abc.war $file
2.  insert it back : jar -uvf abc.war $file

BASICS


tput
It is used to clear screen , if you give it as it it doesn't work

tput clear : it clears the screen, most unix systems simply offers clear command.


ps
See the processes

wc
word count

the file contains 6 line , 6 words and 42 characters

• wc -l filename.txt : count lines
• wc - w filename.txt : count words
• wx -c filename.txt : count characters

cmp
Can compare two files

• if two files identical no output message
• if difference

comm : whats common in two files







diff
tells you what you need to do , to make files common


echo * & ls


ls options


-F : notice the * tells its an executable , the / tells its a directory and remaining are normal.
-x : multi columnar display



-R is recursive
-r is display in reverse order
-d : display only the directory name
-t : sort file by lat modification time
-u : sort file name by last access time
- i : display inode number

cat
- v : display non printing character
- n : display line numbers

cp & rm
-i : interactive
-R : recurisve

What is inode ?
An inode is an entry in inode table, containing information ( the metadata ) about a regular file and directory. An inode is a data structure on a traditional Unix-style file system such as ext3 or ext4.



Note that

• cp adds an inode number
• mv doesn't disturb inode number but changes file name
•  rm deletes both file and  inode

Different pagers

• pg : now obsolete
• more : berkley's original
• less : mostly available on all linux machines, more powerful and is vi based

tar command

• -c : create archive
• -x : extract from archive
• -t : display files in archive
• -f arch : specify the archive 
• -v : verbose

tar -zcvf tar-archive-name.tar.gz source-folder-name 
zip myZipFileName.zip abc.html xyz.txt

chmod

Similarly chmod ugo+x abc.txt





Similarly there is

• chown
• chgrp

VI Editor

• execute mode
• input mode

input mode commands

• i : input to left of cursor
• a : input to right of cursor
• I : insert at begining of line
• A : insert at end of line
• o : opens line below
• O : opens line above
• rch :  replace single character under cursor with ch
• R : replace text from cursor to Right
• s : replace single character with cursor with any number of characters
• S: Replace entire line

Quiting

• :w saving your work ( writes buffer to disk )
• :wq or :x : save and quit your work
• :q : doesnt work if buffer is not saved
• :q! : buffer is changed if you still want to abandon change

more

• x : delete a character
• dd : deletes a line
• 6dd : deletes current line and 5 lines below
• n : repeat search in current direction
• N : search in opposite direction 

find   

find

• find . -name abc.txt
• find . -iname abc.txt (case insensitive search)
• find . -name '*.txt'
• find . -type f -name abc.txt (to find file with name abc.txt)
• find . -type f -perm 0777 -print  (find file with all permissions) (777 = owner group others )
• find . -type f ! -perm 0777 -print
• find . -perm /a=x (find all executable)
• find . -perm /u=r (find all read only)
• find . -type f -perm 0777 -exec chmod 755 {} \; ( find files with permission 777 & change it to 755)
• find . -type f -empty -exec rm -f {} \; ( find empty files and delete it )
• find . -type f -name “.*” (find all hidden files )
• find . -type f -mtime 10 ( find files that are modified 10 days back )
• find . -type f -atime 10 ( find files that were accessed 10 days back )
• find . -type f -mtime +10 -mtime -20 ( find files that are modified 10 days back & less than 20 days )
• find . -mmin 1 (find files modified 1 min back )
• ( -1 means less than 1 day , +1 more than 1 day)
• find . -user root -name “*.txt”
• find . -group developer -name “*.txt”
• find . -size -1M ( find files that are less than 1 MB )
• find . -size +1M . -size -3M ( find files that are more than 1MB & less than 3 MB )
• find . -type f -name “*.txt” >> /dev/null (redirect error to /dev/null i.e. dont show on screen)
• find . -type f -not -name “*.txt” ( find files not txt files)
• find / -maxdepth 1 -type f -not -name “*.txt” (notice maxdepth)
• find . \(-name “*.txt” -o -name “*.html” \) -exec rm -f {} \;

grep

1. grep "regularExpression4string2search" "filePattern*.txt"
2. -i : for case insensitive search
3. -w : for full word search
4. -A N : display N lines after match
5. -B N : didplay N lines before it
6. -C N : display N lines around 
7. -r : recursive searching
8. -v : invert searching (grep -v "main" * | wc -l  ... search files with not word main )
9. -c : count number of matches
10. -I : display filename with matches pattern
11. -o : show position of matching word
12. -n : show number while displaying output

llalc2@ABC~/temp
$ grep -c "one" *
abc.txt:1
hello.txt:1

llalc2@ABC ~/temp
$ grep -c "threes" *
abc.txt:0
hello.txt:1

llalc2@ABC ~/temp
$ grep -v "threes" *
abc.txt:one
abc.txt:two
abc.txt:three
abc.txt:four five
abc.txt:six
hello.txt:one
hello.txt:two
hello.txt:four five
hello.txt:six

shells
there are different types of shells

• korn shell
• sh : the primitive bourne shell
• csh : C shell
• bash shell : very powerfull and recommended for use.