Shell Programming and Scripting

#!/usr/bin/env bash

# @(#) s1	Demonstrate tcl regular expression string extraction.
# For examples on regexp, see:
# http://wiki.tcl.tk/989

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C tclsh

FILE=${1-data1}

pl " Input data file $FILE:"
cat $FILE

pl " Demo code for tcl:"
cat tcl1

pl " Results:"
./tcl1 < $FILE

exit 0

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39
tclsh 8.4

-----
 Input data file data1:
<domain>?a=12345&d=somestring1(Note: c not present)
<domain>?c=10.10.10.100&d=somestring1
<domain>?a=12345&b=somestring1&c=10.1.2.4&d=somestring2
<domain>?a=12345&c=10.1.2.4&b=somestring1&d=somestring2

-----
 Demo code for tcl:
#!/usr/bin/env tclsh

# @(#) tcl1     Demonstrate regexp extraction of matched string.

puts stdout ""
if { $argc == 0 } then {
  puts stdout " No command line parameters provided."
} else {
  set i 0
  foreach arg $argv {
    set m1 " $i $arg"
    incr i
    set m2 ""
    if { [ file exists $arg ] } then {
      set m2 [ join [ list "(" [ file type $arg ] ")" ] ]
    }
    puts stdout "$m1 $m2"
  }
}

while { [gets stdin line] >= 0} {
  set ip " "
  regexp {c=([0-9]*\.[0-9]*\.[0-9]*\.[0-9]*)} $line -> ip
  if { $ip != " " } {
    puts $ip
  } else {
    puts " Missing ip on $line"
  }
}

exit 0

-----
 Results:

 No command line parameters provided.
 Missing ip on <domain>?a=12345&d=somestring1(Note: c not present)
10.10.10.100
10.1.2.4
10.1.2.4