% gdb -core tr.core `which tr`
Reading symbols from /usr/bin/tr...Reading symbols from /usr/libdata/debug//usr/bin/tr.debug...done.
done.
[New process 1]
Core was generated by `tr'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000075cac02c13dc in __getenvslot (name=name@entry=0x7f7fffad2a00 "STDBUF0", l_name=l_name@entry=7, allocate=allocate@entry=false)
    at /usr/src/lib/libc/stdlib/_env.c:260
260             while (environ[num_entries] != NULL) {
(gdb) bt
#0  0x000075cac02c13dc in __getenvslot (name=name@entry=0x7f7fffad2a00 "STDBUF0", l_name=l_name@entry=7, allocate=allocate@entry=false)
    at /usr/src/lib/libc/stdlib/_env.c:260
#1  0x000075cac02c157b in __findenvvar (name=name@entry=0x7f7fffad2a00 "STDBUF0", l_name=l_name@entry=7)
    at /usr/src/lib/libc/stdlib/_env.c:332
#2  0x000075cac02c0f84 in getenv (name=name@entry=0x7f7fffad2a00 "STDBUF0") at /usr/src/lib/libc/stdlib/getenv.c:73
#3  0x000075cac0323c20 in __senvbuf (fp=0x75cac05780c0 <__sF>, couldbetty=0x7f7fffad29f0, size=0x7f7fffad29f8)
    at /usr/src/lib/libc/stdio/makebuf.c:74
#4  __smakebuf (fp=fp@entry=0x75cac05780c0 <__sF>) at /usr/src/lib/libc/stdio/makebuf.c:133
#5  0x000075cac0312640 in __srefill (fp=fp@entry=0x75cac05780c0 <__sF>) at /usr/src/lib/libc/stdio/refill.c:119
#6  0x000075cac03123c5 in __srget (fp=0x75cac05780c0 <__sF>) at /usr/src/lib/libc/stdio/rget.c:62
#7  0x00000001cb602018 in main (argc=<optimized out>, argv=0x7f7fffad2b48) at /usr/src/usr.bin/tr/tr.c:142
(gdb) f 7
#7  0x00000001cb602018 in main (argc=<optimized out>, argv=0x7f7fffad2b48) at /usr/src/usr.bin/tr/tr.c:142
142                     for (lastch = OOBCH; (ch = getchar()) != EOF;)