Useful unix character sequences

• In "unix," to monitor system calls, use strace or truss.
• In "C++", to string out in full justified hex with type safety:
  
  

  my_type val = foo;
  
  cout << hex << setiosflags(ios::right) << setw(2*sizeof(my_type)) << val << endl;

• In "linux," to scan for hosts in local domain:

  nmap -sP 192.168.1.1-255

• In "linux," to download an http file without a browser, use wget.
  
• In "emacs", to do regular expression replacement, i.e.,
  of x? --> y?

  
  M-x query-replace-regexp RET
  x\([0-9]\) RET
  y\1 RET

• In "emacs" to manipulate rectangular regions, mark first corner, move to second,
  
  

  Ctrl-x r k (kill)
  Ctrl-x r y (yank).

• to view ps with the full process inheritance tree, try
  
  ps -faux
  
  
• to print strings inside a binary try:
  
  strings < binary >
  
  
• to print symbols inside a binary try:
  
  nm < binary >
  
  
• to look inside an rpm:
  
  rpm -q -l -p < .rpm file >
  
  
• to goto page inside Acrobat Reader 7.0:
  
  shift-ctrl-N
  
  
• In "sh," to call another program, blah, with the same arguments that were passed to the shell script:

#!/bin/sh
blah $*

or

#!/bin/sh
blah "$@"

which also passes arguments with embedded character sequences.
 

• In "gcc," to show all of the macros that are defined for a given platform:

gcc -dM -E test.c


• In "gas," to show macro expansion listings



gas foo.s -ahlm



• to spy on officemates:
  
  /usr/sbin/tcpdump -X -s 0 src ip_address | more
  
  
• to spy on net connections machines or processes: nmap or netstat -anp



• In "emacs," to enable conservative indentation, add this to your .emacs files
  

  add-hook 'c++-mode-hook
            (function (lambda ()
                         (c-set-style "k&r")
                         (setq c-basic-offset 2)
                      )))

  for more information, look at

  "/usr/uns/share/emacs/19.34/lisp/cc-mode.el"
   

• In emacs, to show last typed commands: C-h l
  
• In "gcc," stringification:
  

  #define WARN_IF(EXP) \
  do { if (EXP) \
    fprintf (stderr, "Warning: " #EXP "\n"); }
  while (0)
   

• In "emacs," to create a macro :     Ctrl-X "(" keys Ctrl-X ")"     Ctrl-X "(" keys Ctrl-X ")"

 
• In "emacs," to run the macro :
  
      Ctrl-X e
  
  
• In "emacs," to create a .emacs entry corresponding to a key sequence :


    see emacs faq, #116


• In "make," to run a command without having it barf on error :
  
      rule:
        -mkdir blah
   
• In "gmake," fancy automatic variables.



%.s:  %.S
     $(RGCC) -E $< -o $@


%.lnk: %.o
  $(GEO) link 0 16 0 $^ libarch.a -o $@

• In "gmake," a strlen function.

  strlen = $(strip $(shell /bin/echo -n $(1) | /usr/bin/wc -c))
  
  MAX_FIGURE = 10
  FIGURE_DIGITS := $(call strlen,$(MAX_FIGURE))

• To use CVS over ssh:

  setenv CVS_RSH ssh
  alias cvs cvs -d :ext:user_name@host:cvsroot_path

• To see what happened in the CVS repository between two and four hours ago:
  
  cvs diff -D "2 hour ago" -D "4 hour ago"



• LD_LIBRARY_PATH can be overridden by /etc/ld.so.conf, followed by
  
  ldconfig to update the .so cache



• When your terminal gets messed up because you tried to print out binary stuff, type "reset"



• ps, so that more does not get screwed up: ps -www -aux | more



• To capture screen in X.

  xwd > blah
  xpr blah > blah.ps
  use xv to convert to ppm or whatever
  

• To sync up the times when make sucks.

          rdate < time server >
   

• To highlight a zephyr message, hold down shift.



• OpenPBS commands
  
  qsub -V -I -q short -l nodes=1:dual2.2GHz (interactive, dual 2.2 GHz)
  pbsnodes -a (list servers)
  qstat -Q (list queues)
  qsub -1 node=foo



• To view x resources: editres



• To check for non-updated files with cvs:

  bash -c "cvs status 2> /dev/null | grep Status | grep Need"




• To get the time on unix systems:

  #include < stdio.h>
  #include < stdlib.h>
  #include < dlfcn.h>
  #include < sys/time.h>
  #include < unistd.h>
  
  typedef unsigned long long UInt64;
  
  UInt64 current_microseconds()
  {
    struct timeval tv;
    struct timezone tz;
  
    gettimeofday(&tv,&tz);
    return (tv.tv_sec*1000000 + tv.tv_usec);
  }

  
  On x86-linux machines, there's a macro that accesses the
  machine's cycle counter. It's higher resolution but not as portable.
  You also have need to know the frequency of the machine.

  #include < asm/msr.h >
  {
    UInt64 time;
    rdtscll(time);
    printf("%llu cycles\n",time);
  }