Command Combination
Conversion of number system in Linux shell
Using double brackets with echo, print, printf
To Decimal
echo $((2#00000001)) = 1
echo $((16#AB)) = 171
echo $((8#70) = 56
print $((8#70))
printf “%d\n” $((8#70)). %d = decimalUsing obase,ibase and bc
Character in hex must be uppercase
echo “obase=10; ibase=16; AB” | bc
echo “obase=2; ibase=16; F” | bc===========================================================================================================
Compare files
Comm
comm file1 file2
First column: Line not present in file1
Second column: line not present in file2
Third column: file present in both
Diff
diff file1 file2 [-u | -c]: unified or context format
-: line appears in first file only
+: line appears in second file only
Some Options
-y: compare side by side
Vimdiff
open multiple files in multiple vim windows
do: gets changes from the other window into the current one
dp: puts the changes from the current window into the other one
]c: jumps to the next change
[c: jumps to the previous change
C w: switches to the other split window.
===========================================================================================================
Combination usage of sed, awk, cut, paste, cat, echo, grep
Combine each 2nd line to the line before it
Original data
Using AWK
Using Sed
Using Paste
Extract 1 line and all indented lines below it
Original data
Using AWK
Print range of character from each line
cut -c 1-N
Check IP address of domain and print out domain, ip address or domain, not found
while read -r domain; do ip=$(host "$domain" | awk '/has address/ {print $4}'); echo "$domain,${ip:-not found}"; done < domains.txt
===========================================================================================================
Testing SMTP, SMTPS, HTTP, HTTPS using CLI commands
SMTP
SMTPS
Using SSL
Using TLS
other utilities
telnet-ssl: apt install telnet-ssl
gnutls-cli: apt install gnutls-cli
HTTP
HTTPS
Reference
https://unix.stackexchange.com/questions/184340/how-to-grep-a-line-with-unknown-number-of-its-indented-lines
https://qmail.jms1.net/test-auth.shtml
https://www.samlogic.net/articles/smtp-commands-reference-auth.htm
https://www.ndchost.com/wiki/mail/test-smtp-auth-telnet
Last updated