Ask HN: Best Unix Tricks?

    :(){ :|:& };

Anyway, on a more serious note, after an installation procedure that was a lot of work, if you want to document the whole thing use:

    history | cut -d ' ' -f 5-

It's not a 'great killer unix tip', but it works for me.

Edit: Another one just came to mind, the ps command has a very useful option that is quite undervalued imo:

    ps ax --forest

  !!:s/sl/ls

  !!:gs/sl/ls

Starts a search through your history file.

  set -o vi # vi like behaviour of the command line.

  cat > somefile.txt <<EOF # quickly creates a text file

$CDPATH is also amusing:

  $ mkdir /foo/bar/baz
  $ cd baz
  bash: cd: baz: no such file or directory
  $ export CDPATH="/foo/bar"
  $ cd baz
  $ pwd
  /foo/bar/baz

sudo !! (Run the last command as root)

:w !sudo tee % (Save a readonly file in VIM)

> tmp.file (Empty a file)

cmd !$ (Run cmd with previous commands arguments)

They are just some of my favorites.

    > make me a sandwich
    what? make it yourself
    > sudo !!
    okay

For example:

  curl http://news.bbc.co.uk/ | pbcopy # copies a web-page to clipboard

  pbpaste | sort | pbcopy # sort the contents of the clipboard.

  open file.pdf

  open music.mp3

The 4.4 BSD supplementary books (PSD, USD, SMM, etc.) are full of major documentation, with chapters on vi, awk, cc, yacc, gprof, etc. They're very old-school. (OpenBSD installs them with its default documentation, I think FreeBSD does as well.) Some parts will be obsolete, but the big ideas are the same. For example, it covers lex and yacc better in about ten pages each than the O'Reilly book could in twenty times that. Same with make, and several other major parts in the Unix toolchain.

For starters, learn to use: apropos, cron, the basics of sed and awk, the shebang, a real editor, screen or tmux, tar, gzip, and find. Read man pages, see where they lead you. Try to automate stuff, and go spelunking in the infrastructure for whatever Unix distro you use.

I also found that I learned a LOT by getting away from stuff that assumed Linux. Soooo much Linux newbie stuff is written by people who only know Linux (and may use GNOME for most things, really). You don't really learn Unix that way. Also, watch out for people who assume that bash is the standard shell. (A pet peeve of mine.)

    xargs -d '\n'

    find * -type f | egrep -i '\.(gif|jpg|png)$' | xargs -d '\n' identify

For example:

ps -e | grep processname

will grab the pid of any process so that you can subsequently kill it.

sudo !! (run last command as sudo) is great too when you forget to type sudo on a regular basis like me.

    tar cf - * | (cd <dest-dir> ; tar xf - )

    cd ...

    cd ../..

    cd .....

http://blog.jerodsanto.net/2009/09/cd-up-up-up/

Actually, I rather hope there's something better than strace for the latter. But it works.

  # a visual recursive list of all files and directories
  function tree()
  {
    find . | sed -e 's/[^\/]*\//|--/g' -e 's/-- |/    |/g' | $PAGER
  }

  # recursive text search (ack is also nifty)
  function f()
  {
    find . -name '*' | xargs grep -l $1
  }

  # recursive search and replace (ignoring hidden files and dirs), example: replace foo bar
  function replace()
  {
    find . \( ! -regex '.*/\..*' \) -type f | xargs perl -pi -e "s/$1/$2/g"
  }

2. Learn to use the editor modes on your shell. If you use Emacs mode in zsh, for example, things like transient-mark mode work with all the standard Emacs keybindings, and you can easily copy and paste pieces of your command line. vi mode also supports similar bells and whistles.

3. In zsh, if you are typing a command and then realize you need to look up its man page, move your cursor back to the command and hit Esc-h (or Meta-h or Alt-h, depending on your terminal). Once you quit the man viewer, your command line will be restored.

4. In zsh, if your command line gets too unwieldy to edit in zle, just hit Esc-e (Meta-e). It'll let you edit the command line in your editor (be sure your EDITOR environment variable is set).

5. zsh has an awesome buffer stack feature. Imagine you're typing a long command (call it command A), then realize that you need to run something else first (call it command B). Don't Ctrl-u or delete anything; leave your current command alone, and hit Esc-q. You'll get a fresh prompt. Run B. Once B executes, zsh will restore the command line from A. You can do this as many times as you want.

Anyway --- go and read "From Bash to Z Shell, Conquering the Command Line" by Kiddle, Peek, and Stephenson. I've never seen a better book on using shells with maximum efficiency (and I'm still only learning). Just learning to use and extend the autocompletion features of zsh was invaluable to me.

print the names of all the files satisfying fileregex with text satisfying textregex. Nice if you need to find out where a function is defined.