One Day One Cmd

Place for playing with commands…

Monthly Archives: February 2011

Day 56: $ less

ODOC: bala@bala:~ less
Less is a program similar to more, but which allows backward  movement in the file as well as forward movement.  Also, less does not have to read the entire input file before starting,  so  with  large  input files it starts up faster than text editors like vi.

Options:
Most options may be changed either on the command line, or from within less by using the – or — command. Options may be given in one of two forms: either a single character preceded by a -, or a name preceeded by –.

FINDING:

  -a  ........  --search-skip-screen
                  Forward search, skips current screen.
  -g  ........  --hilite-search
                  Highlight only last match for searches.
  -G  ........  --HILITE-SEARCH
                  Don't highlight any matches for searches.
  -h [N]  ....  --max-back-scroll=[N]
                  Backward scroll limit.
  -i  ........  --ignore-case
                  Ignore case in searches.
  -I  ........  --IGNORE-CASE
                  Ignore case in searches and in search patterns.
  -j [N]  ....  --jump-target=[N]
                  Screen position of target lines.
  -p [pattern]  --pattern=[pattern]
                  Start at pattern (from command line).
  -t [tag]  ..  --tag=[tag]
                  Find a tag.
  -T [tagsfile] --tag-file=[tagsfile]
                  Use an alternate tags file.
  -y [N]  ....  --max-forw-scroll=[N]
                  Forward scroll limit.
Line Editing:

        These keys can be used to edit text being entered
        on the "command line" at the bottom of the screen.

RightArrow                 ESC-l     Move cursor right one character.
LeftArrow                  ESC-h     Move cursor left one character.
CNTL-RightArrow ESC-RightArrow ESC-w Move cursor right one word.
CNTL-LeftArrow  ESC-LeftArrow  ESC-b Move cursor left one word.
HOME                       ESC-0     Move cursor to start of line.
END                        ESC-$     Move cursor to end of line.
BACKSPACE                            Delete char to left of cursor.
DELETE                     ESC-x     Delete char under cursor.
CNTL-BACKSPACE ESC-BACKSPACE         Delete word to left of cursor.
CNTL-DELETE ESC-DELETE     ESC-X     Delete word under cursor.
CNTL-U     ESC (MS-DOS only)         Delete entire line.
UpArrow                    ESC-k     Retrieve previous command line.
DownArrow                  ESC-j     Retrieve next command line.
TAB                                  Complete filename & cycle.
SHIFT-TAB                ESC-TAB   Complete filename & reverse cycle.
CNTL-L                               Complete filename, list all.

Ex: $ man pwd | less +/print
Output:
View the man page for the pwd command; begin at the first appearance of the word “print

Day 55: $ lsusb

ODOC: bala@bala:~ lsusb
It is a utility for displaying information about USB buses in the system and the devices connected to them. For specific bus use -s with id no.

Ex: $ lsusb

Day 54: $ locale

ODOC: bala@bala:~ locale It shows information about the current locale environment or all locales to standard output.

Ex: $ locale -a

option: -m (for available charmaps)

Day 53: $ grep -r

ODOC: bala@bala:~ Grep command searches the given file for lines containing a match to the given strings or words. By default, grep prints the matching lines. Use grep to search for lines of text that match one or many regular expressions, and outputs only the matching lines. -r used for recursive.

Ex: $ grep -r welcome *
Output:

/home/user/Desktop/file.txt:Welcome to “ODOC”
/media/Ubuntu/new.py: welcome to python

 

Day 52: $ grep

ODOC: bala@bala:~ Grep command searches the given file for lines containing a match to the given strings or words. By default, grep prints the matching lines. Use grep to search for lines of text that match one or many regular expressions, and outputs only the matching lines.

Ex: $ grep welcome first.txt
Output: Welcome to “ODOC”

It will find the string related to welcome in first.txt and prints the line.

 

Day 51: $ Pipe

ODOC: bala@bala:~ A pipe is a means by which the output from one process becomes the input to a second. In technical terms, the standard output (stout) of one command is sent to the standard input (stdin) of a second command. If you are not sure of the advantages this creates, then let’s look at a simple example.

Ex: $ echo Hello World! | rev
output: !dlroW olleH

Day 50: $ Repeat the Commands.

ODOC: bala@bala:~ Commands can be repeated for several time using ‘for’. The structure is for varname in list; do commands…………; done

Ex-$ for file in *.txt do mv-v .old; done
Output:
first.old.txt