$re = '/.*(\w{4}\d{7}).*/mD';
$str = 'UNB+UNOA:2+RCW OPS CENTER+TERMINAL+180808:1519+1533741570C3ED+++++RCW OPS CENTER\'UNH+01533741570BAP+BAPLIE:D:95B:UN:SMDG22\'BGM++CAPSTAN4.20180808151930+9\'DTM+137 1808081519UTC:301\'TDT+20+081S+++HSD:172:166+++9V7575:103:ZZZ:xxxx xxx\'LOC+5+BRSSA:139:6\'LOC+61+COCTG:139:6\'DTM+178:1808090412 :201\'DTM+133:1808091512:201\'DTM+132:1808180041:201\'RFF+VON:081N\'LOC+147+0380412::5\'MEA+WT++KGM:29515\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+DOHAI:139:6\'RFF+BM:1\'EQD+CN+
SUDU8505087+45G1+++5\'NAD+CA+HSD:172:20\'LOC+147+0380312::5\'MEA+WT++KGM:29586\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+DOCAU:139:6\'RFF+BM:1\'EQD+CN+
UACU5363691+45G1+++5\'NAD+CA+HLC:172:20\'LOC+147+0380212::5\'MEA+WT++KGM:29591\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+COCTG:139:6\'RFF+BM:1\'EQD+CN+
TGHU9702812+45G1+++5\'NAD+CA+MSC:172:20\'LOC+147+0380112::5\'MEA+WT++KGM:29616\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+DOCAU:139:6\'RFF+BM:1\'EQD+CN+
HLXU6240079+45G1+++5\'NAD+CA+HLC:172:20\'LOC+147+0380414::5\'MEA+WT++KGM:29476\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+PRSJU:139:6\'RFF+BM:1\'EQD+CN+
HASU4556735+45G1+++5\'NAD+CA+HSD:172:20\'LOC+147+0380314::5\'MEA+WT++KGM:29476\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+DOHAI:139:6\'RFF+BM:1\'EQD+CN+
SUDU6787839+45G1+++5\'NAD+CA+HSD:172:20\'LOC+147+0380214::5\'MEA+WT++KGM:29481\'LOC+9+BRSSA:139:6+TECSV\'LOC+11+COCTG:139:6+TCC\'LOC+83+COCTG:139:6\'RFF+BM:1\'EQD+CN+...';
$subst = "$1\r\n";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php