UNIX-commands

Usefull Commands

• TAB: complete filename or command up to the point of uniqueness
• CTRL-u: cancel whole line
• CTRL-c : cancel the processes after it has started
• CTRL-n: ** go forwards in the history of commands**. You can also use the cursor down key for this.
• exit: Ends your work on the UNIX system
• CTRL-l or clear: Clear the screen
• CTRL-z: Pause the currently running program
• CTRL-a: Jump back to first character in line
• CTRL-e: Jump forward to last character in line

File Commands

List your files

• ls: lists your files
• ls -l: lists your files in 'long format', which contains lots of useful information (exact size , owner etc).
• ls -a: lists all files, including the ones whose filenames begin in a dot, which you do not always want to see.

Create file

• touch <filename: create or update file

File

• more <filename>: shows the first part of a file, just as much as will fit on one screen. Just hit the space bar to see more or q to quit. You can use /pattern to search for a pattern.
• emacs <filename>: is an editor that lets you create and edit a file. See the emacs page.
• mv <filename1> <filename2>: moves a file (i.e. gives it a different name, or moves it into a different directory.
• cp <filename1> <filename2>: copies a file
• rm <filename>: removes a file.
• rm -i <filename>: removes a file but before ask for confirmation
• diff <filename1> <filename2>: compares files, and shows where they differ
• wc <filename>: tells you how many lines, words, and characters there are in a file
• chmod options <filename>: lets you change the read, write, and execute permissions on your files. chmod settings

Find

• find <filename/directory>: find a file or directory
• find . -name FILE -print: Find all paths containing FILE in the current directory or below it

File Compression

• gzip <filename>: compresses files
• gunzip <filename>: uncompresses files compressed by gzip
• gzcat <filename>: look at a gzipped file without gunzip it. same as gunzip -c.
• gzcat <filename> | lpr: print it directly

List of options commonly used

• a (all) — Lists all files in the directory, including hidden files (.filename). The .. and . at the top of your list refer to the parent directory and the current directory, respectively.
• l (long) — Lists details about contents, including permissions (modes), owner, group, size, creation date, whether the file is a link to somewhere else on the system and where its link points.
• F (file type) — Adds a symbol to the end of each listing. These symbols include /, to indicate a directory; @, to indicate a symbolic link to another file; and /*, to indicate an executable file.
• r (reverse) — Lists the contents of the directory in reverse sort order.
• R (recursive) — Lists the contents of all directories below the current directory recursively.
• S (size) — Sorts files by their sizes.

Directory Commands

• cd <directory name>: **Go to the directory **
• rm -r <directory name>: Remove a directory with files (not hidden files)
• rm -rf <directory name>: Remove a directory with all files (also hidden)
• open .: Open current directory

Specials

• cp *.JPG <directory name>: Copy all jpg images in directory to another directory

Cat command

Cat(concatenate ) command is very frequently used in linux.It reads data from file and give their content as output

• cat filename: to view a single file
• cat file1 file2: to view multiple files
• cat -n filename: to view contents of a file preceding with line numbers