Hello,
If you execute gsmctl with no arguments, you will receive information of usable commands with gsmctl
-S -r, --sms --read <INDEX> Read SMS by index
-S -l, --sms --list <TYPE> List SMS by type [all, read, new]
-S -t, --sms --total Print SMS memory usage
-S -d, --sms --delete <INDEX> Delete SMS by index
-S -s, --sms --send "<NUMBER> <TEXT>" Send SMS. IMPORTANT! Number and text must be within quotes
-S -p, --sms --sendpdu "PDU" Formed PDU will be send straight to modem
-S -b, --sms --send-b64 <NUMBER> Send SMS encoded in base64 from /tmp/.smstext
gsmctl -S -l all command should list all received SMS messages.
Or, you can use logread -f | grep SMS to catch an event of SMS being received via command line.