Text tools in Linux

Here is the list of essential Linux text tools with short description of their functions

• cat - shows file in standard output
• tac - shows file in standard output in reverse order
• join - combines files by field
• paste - merges files line by line
• expand - converts tabs to spaces
• od - dump files in octal and other formats
• sort - sort text files, sing fields(symbolic or numerical)
• split - splits files to pieces by bytes or by number of lines.
• tr - translate or delete characters
• unexpend - convert spaces to tabs
• uniq - delete duplicate lines
• fmt - simple text formatter, for example it splits long lines.
• nl - number lines in a file
• pr - convert text files for printing.
• head - shows the beginning of the file.
• tail - shows some from the end of the file.
• less - text file reader.
• cut - remove sections from each line of files
• wc - counts lines, bytes and words
• sed - stream editor
• grep - print lines matching a pattern
• egrep - grep with activated(-E option) extended regular expressions
• fgrep - fixed-string grep

And here are the main Vi commands

Command mode:

• p - paste text
• 3yy - copy 3 lines
• 3dd - delete 3 lines
• u - undo
• h,j,k,l - move cursor
• o - insert new line and enter insert mode
• i - enter insert mode before cursor
• R - enter insert mode for text replacement
• a - append text after cursor
• / - search forward
• ? - search backward
• c - change text
• G - goes to specified line
• :%s/original/replacement - replace globally
• Ctrl+F - move one screen ahead
• Ctrl+B - move one screen back
• Ctrl+D - go down half screen
• Ctrl+U - go up half screenExec mode:
• e or e! - edit another file
• r - include file
• ! - execute external command
• q - quit
• w - save
• ZZ - save and exit

Tips
To translate Windows/Dos text file, where CR+LF are the end of the line, to Linux text file, where LF is the end of a line, tr program can be used:

tr -d '\r' < input_file > output_file