Using boolean expression Bash script


 
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# 8  
Old 02-12-2016
Ooohh - you're after the netmask. Try
Code:
{ read IP1; read IP2; } < file1
BIP1=$(( 0x$(printf "%02X" ${IP1//./ })))
BIP2=$(( 0x$(printf "%02X" ${IP2//./ })))
TMP=$(( BIP1 ^ BIP2 ))
I=1
while [ $(( I*=2 )) -lt $TMP ]; do :; done                           
I=$(( --I ^ 2**32-1 ))
printf "%d.%d.%d.%d\n" $((I>>24)) $((I>>16&255)) $((I>>8&255)) $((I&255))
255.255.224.0

---------- Post updated at 14:30 ---------- Previous update was at 14:13 ----------

or
Code:
{ read IP1; read IP2; } < file1
BIP1=$(( 0x$(printf "%02X" ${IP1//./ })))
BIP2=$(( 0x$(printf "%02X" ${IP2//./ })))
TMP=$(( BIP1 ^ BIP2 ))   
while (( TMP )); do TMP=$((TMP>>1)); ((I++)); done
I=$((2**32-1 ^ 2**I-1))
printf "%d.%d.%d.%d\n" $((I>>24)) $((I>>16&255)) $((I>>8&255)) $((I&255))

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RBASH(1)						      General Commands Manual							  RBASH(1)

NAME
rbash - restricted bash, see bash(1) RESTRICTED SHELL
If bash is started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. It behaves identically to bash with the exception that the follow- ing are disallowed or not performed: o changing directories with cd o setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV o specifying command names containing / o specifying a filename containing a / as an argument to the . builtin command o specifying a filename containing a slash as an argument to the -p option to the hash builtin command o importing function definitions from the shell environment at startup o parsing the value of SHELLOPTS from the shell environment at startup o redirecting output using the >, >|, <>, >&, &>, and >> redirection operators o using the exec builtin command to replace the shell with another command o adding or deleting builtin commands with the -f and -d options to the enable builtin command o using the enable builtin command to enable disabled shell builtins o specifying the -p option to the command builtin command o turning off restricted mode with set +r or set +o restricted. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script. SEE ALSO
bash(1) GNU Bash-4.0 2004 Apr 20 RBASH(1)