A few useful Unix Commands

• Helpful Unix Commands
• Files
  • Compression
• Directories
  • Paths
• Linux

Helpful Unix Commands

• who
  "who" - those currently using the system
• users
  "users" - account names of people using the system
• whoami
  whoami (no spaces) - this commands lists the account name associated with the current login
  
• who am i
  who am i (with spaces) host name and domain name (name of computer and internet address of computer), account name, communication line, and date
  
• date
  gives current date
• time
  gives execution time of last command
• ls
  list files (-s for size in K, -a for all files, -F for file types, -m gives a comma separated list, ls -l gives a full listing, and shows permissions)
• env
  To view your environment - the user environment is a collection of specially named variables that have specific values
• rm
  to delete a file:
  syntax:    rm name_of_file
  
• rm -i
  to delete a file with confirmation
  
• cd
  to move into a directory:
  syntax:    cd name_of_directory
  
• mkdir
  to make a new directory:
  syntax:    mkdir name_of_new_directory
  
• cd ..
  to move back a directory level:
  syntax:    cd ..
  After you have done the above command, check to see where you are by entering pwd
  
• mv
  to rename a file:
  syntax:    mv old_filename new_filename
  
• pwd
  pwd tells you where you are. It tells you the names of all the directories above you.
  
• csh
  lance un nouveau shell
  C-shell has the prompt %, Bourne-Shell uses $.

Files

• cp
  to copy a file into the next directory:
  syntax:    cp name_of_file name_of_directory
  
• cp -i
  copy with confirmation
  
• cmp
  compares two tex files
  
• diff
  compares two directories
  
• head
  print the first lines on screen
  
• tail
  print the last lines on screen
  
• nl
  list a file with numbered lines
  
• sort
  sort lines by alphabatic order on screen
  
• sort -r
  sort in reverse order
  
• sort -n
  sort on first numerical word
  
• sort -o
  sort and write in another file
  
• sort -f
  sort in neglecting case
  
• sort -b
  sort in neglecting initial spaces
  
• cat nam1 nam2 > nam3
  concatenates 2 files in a third one
• cut -b l1 l2 file
  extracts columns from l1 to l2 from file on screen
  
• cut -b l1 l2 filin > filout
  extracts columns from l1 to l2 from filin to filout
  
• chmod ugo+wrx
  modifies protections (user, group, other; write, read, execute)
  
• chown
  changes owner of files
  

Compression

• compress
  compress file
  
• uncompress
  uncompress file
  
• gzip
  gnu-zip compress file
  
• gunzip
  gnu-zip uncompress file
  
• uuencode
  code file from binary to ascii
  useful to send a compressed file(binary) on mail
  
• uudecode
  decode file
  

Directories

• quota -v
  informs you of space available on disk for you
  
• du -s
  gives sizes of directories at this level, in blocks=512Ko
  

Paths

• cd
  returns in your home directory
  
• .
  is the current directory
  
• ..
  is the directory above
  
• cp -r /rep1/rep2/* .
  copies all a hierarchy in the current directory
  
• dircmp
  compares two directories
  
• find orig -name < file > -print
  search a file in the tree below orig, and print the path
  
• find /rep1/rep2 -atime -60 -name "*.ps" -print
  search all .ps files in the tree below /rep1/rep2, created less than 60 days ago, and print them
  
• grep " nam " *
  search for nam in all files of present directory
  
• grep copying help
  This searches the file help for the string copying and displays each line on your terminal
  
• ls -l | grep '^d........x'
  To use the output of another command as input to the grep command:
  This lists all the directories in the current directory for which other users have execute permission. The expression is quoted to prevent the shell interpreting the ^ metacharacter
  
• grep Smith /etc/passwd > smurffs
  To redirect the results of a search to a file, use the ">" command:
  This searches the passwd file for each occurrence of the name Smith and places the results of this search in the file smurffs
  

Linux

Guide to Linux, exhaustive

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