为什么X11输出"connect /tmp/.X11-unix/X1: No such file or directory"
Why does X11 output "connect /tmp/.X11-unix/X1: No such file or directory"
我想默默地测试X11是否在脚本中工作。
即使我使用（例如）xset q > /dev/null 2>&1
将 stdout 和 stderr 重定向到 /dev/null，我仍然收到 "connect /tmp/.X11-unix/X1: No such file or directory"
我 strace 了，它似乎不是由 xset 编写的。我也strace了相关的sshd，好像也没有写。
xset、xdpyinfo和How to check if X server is running?处的测试程序都输出了这个无用的错误信息。事实上，vim 也是如此。但是 "ls" 没有。
我也试过：script -e -c 'xset q' /dev/null > /dev/null 2>&1
...但即使这样也会输出错误消息。
我需要做什么来消除这个过于激进的错误消息？
谢谢！
PS: 这是 xset q 的一个 strace:
20878 execve("/usr/bin/xset", ["xset", "q"], 0x7ffe3e91cfe0 /* 33 vars */) = 0
20878 brk(NULL) = 0x563d8a664000
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=141841, ...}) = 0
20878 mmap(NULL, 141841, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f19ac118000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXmuu.so.1", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]p[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=14528, ...}) = 0
20878 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac144000
20878 mmap(NULL, 2109592, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19abd10000
20878 mprotect(0x7f19abd13000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19abf12000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f19abf12000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXext.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]05[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=73640, ...}) = 0
20878 mmap(NULL, 2169496, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19abaf8000
20878 mprotect(0x7f19abb09000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19abd08000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x10000) = 0x7f19abd08000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libX11.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]07[=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=1277384, ...}) = 0
20878 mmap(NULL, 3374392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19ab7c0000
20878 mprotect(0x7f19ab8f3000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19abaf3000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x133000) = 0x7f19abaf3000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]0[=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0755, st_size=2030544, ...}) = 0
20878 mmap(NULL, 4131552, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19ab3c8000
20878 mprotect(0x7f19ab5af000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19ab7af000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1e7000) = 0x7f19ab7af000
20878 mmap(0x7f19ab7b5000, 15072, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19ab7b5000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libxcb.so.1", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P1[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=162232, ...}) = 0
20878 mmap(NULL, 2257576, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19ab1a0000
20878 mprotect(0x7f19ab1c6000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19ab3c6000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x26000) = 0x7f19ab3c6000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=14560, ...}) = 0
20878 mmap(NULL, 2109712, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aaf98000
20878 mprotect(0x7f19aaf9b000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19ab19a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f19ab19a000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXau.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=14456, ...}) = 0
20878 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac142000
20878 mmap(NULL, 2109720, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aad90000
20878 mprotect(0x7f19aad92000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19aaf92000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f19aaf92000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXdmcp.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=22616, ...}) = 0
20878 mmap(NULL, 2117760, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aab88000
20878 mprotect(0x7f19aab8d000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aad8c000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x4000) = 0x7f19aad8c000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libbsd.so.0", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P4[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=80104, ...}) = 0
20878 mmap(NULL, 2179152, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa970000
20878 mprotect(0x7f19aa983000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aab82000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x12000) = 0x7f19aab82000
20878 mmap(0x7f19aab84000, 80, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19aab84000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/librt.so.1", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=][=11=]\"[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=31680, ...}) = 0
20878 mmap(NULL, 2128864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa768000
20878 mprotect(0x7f19aa76f000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aa96e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6000) = 0x7f19aa96e000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]00b[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0755, st_size=144976, ...}) = 0
20878 mmap(NULL, 2221184, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa548000
20878 mprotect(0x7f19aa562000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aa761000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x19000) = 0x7f19aa761000
20878 mmap(0x7f19aa763000, 13440, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19aa763000
20878 close(3) = 0
20878 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac13d000
20878 mmap(NULL, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac115000
20878 arch_prctl(ARCH_SET_FS, 0x7f19ac115740) = 0
20878 mprotect(0x7f19ab7af000, 16384, PROT_READ) = 0
20878 mprotect(0x7f19aa761000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aa96e000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aab82000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aad8c000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aaf92000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19ab19a000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19ab3c6000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19abaf3000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19abd08000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19abf12000, 4096, PROT_READ) = 0
20878 mprotect(0x563d8872f000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19ac13f000, 4096, PROT_READ) = 0
20878 munmap(0x7f19ac118000, 141841) = 0
20878 set_tid_address(0x7f19ac115a10) = 20878
20878 set_robust_list(0x7f19ac115a20, 24) = 0
20878 rt_sigaction(SIGRTMIN, {sa_handler=0x7f19aa54dcb0, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7f19aa55a890}, NULL, 8) = 0
20878 rt_sigaction(SIGRT_1, {sa_handler=0x7f19aa54dd50, sa_mask=[], sa_flags=SA_RESTORER|SA_RESTART|SA_SIGINFO, sa_restorer=0x7f19aa55a890}, NULL, 8) = 0
20878 rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
20878 prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
20878 brk(NULL) = 0x563d8a664000
20878 brk(0x563d8a685000) = 0x563d8a685000
20878 socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
20878 connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
20878 close(3) = 0
20878 socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
20878 connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
20878 close(3) = 0
20878 openat(AT_FDCWD, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=529, ...}) = 0
20878 read(3, "# /etc/nsswitch.conf\n#\n# Example"..., 4096) = 529
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=304, ...}) = 0
20878 openat(AT_FDCWD, "/etc/host.conf", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
20878 read(3, "# The \"order\" line is only used "..., 4096) = 92
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 futex(0x7f19ab7b7ba4, FUTEX_WAKE_PRIVATE, 2147483647) = 0
20878 openat(AT_FDCWD, "/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=304, ...}) = 0
20878 read(3, "# Dynamic resolv.conf(5) file fo"..., 4096) = 304
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 uname({sysname="Linux", nodename="zareason-limbo", ...}) = 0
20878 openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=141841, ...}) = 0
20878 mmap(NULL, 141841, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f19ac0f0000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P#[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=47568, ...}) = 0
20878 mmap(NULL, 2168632, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa330000
20878 mprotect(0x7f19aa33b000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aa53a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0xa000) = 0x7f19aa53a000
20878 mmap(0x7f19aa53c000, 22328, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19aa53c000
20878 close(3) = 0
20878 mprotect(0x7f19aa53a000, 4096, PROT_READ) = 0
20878 munmap(0x7f19ac0f0000, 141841) = 0
20878 openat(AT_FDCWD, "/etc/hosts", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=403, ...}) = 0
20878 read(3, "127.0.0.1\tlocalhost\n127.0.1.1\tza"..., 4096) = 403
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC, IPPROTO_TCP) = 3
20878 setsockopt(3, SOL_TCP, TCP_NODELAY, [1], 4) = 0
20878 setsockopt(3, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
20878 connect(3, {sa_family=AF_INET, sin_port=htons(6013), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
20878 getpeername(3, {sa_family=AF_INET, sin_port=htons(6013), sin_addr=inet_addr("127.0.0.1")}, [124->16]) = 0
20878 uname({sysname="Linux", nodename="zareason-limbo", ...}) = 0
20878 access("/home/dstromberg/.Xauthority", R_OK) = 0
20878 openat(AT_FDCWD, "/home/dstromberg/.Xauthority", O_RDONLY) = 4
20878 fstat(4, {st_mode=S_IFREG|0600, st_size=827, ...}) = 0
20878 read(4, "[=11=][=11=]zareason-limbo[=11=][=11=]10[=11=]MIT-MAGIC"..., 4096) = 827
20878 read(4, "", 4096) = 0
20878 close(4) = 0
20878 getsockname(3, {sa_family=AF_INET, sin_port=htons(37214), sin_addr=inet_addr("127.0.0.1")}, [124->16]) = 0
20878 fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
20878 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
20878 fcntl(3, F_SETFD, FD_CLOEXEC) = 0
20878 poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
20878 writev(3, [{iov_base="l[=11=]\v[=11=][=11=][=11=][=11=][=11=][=11=][=11=]", iov_len=12}, {iov_base="", iov_len=0}, {iov_base="MIT-MAGIC-COOKIE-1", iov_len=18}, {iov_base="[=11=][=11=]", iov_len=2}, {iov_base="6b57f245!H216J", iov_len=16}, {iov_base="", iov_len=0}], 6) = 48
20878 recvfrom(3, 0x563d8a6660e0, 8, 0, NULL, NULL) = -1 EAGAIN (Resource temporarily unavailable)
20878 poll([{fd=3, events=POLLIN}], 1, -1) = 1 ([{fd=3, revents=POLLIN|POLLERR|POLLHUP}])
20878 recvfrom(3, 0x563d8a6660e0, 8, 0, NULL, NULL) = -1 ECONNRESET (Connection reset by peer)
20878 shutdown(3, SHUT_RDWR) = -1 ENOTCONN (Transport endpoint is not connected)
20878 close(3) = 0
20878 write(2, "xset: unable to open display \"l"..., 47) = 47
20878 exit_group(1) = ?
20878 +++ exited with 1 +++
这是一个类型 -a xset:
$ type -a xset
below cmd output started 2019 Sun Jun 30 07:49:33 AM PDT
xset is /usr/bin/xset
运行 没有重定向，显示消息的顺序：
$ xset q
below cmd output started 2019 Sun Jun 30 08:03:24 AM PDT
connect /tmp/.X11-unix/X1: No such file or directory
xset: unable to open display "localhost:13.0"
为了回应 melpomene 的评论，我设置了一个完全没有启动文件的测试帐户。然后我对它进行 ssh -Y，sudo，并得到与上述相同的错误消息。
我一直在 gnome-terminal 中专门测试。我刚刚尝试了 konsole，但再次收到令人讨厌的错误消息。
我刚刚尝试对 openssh 客户端进行 strace；它产生了一次字符串 "connect"，看起来不相关（除了连接到 ssh 服务器）。
我一直在 Linux Mint 19.1 系统上进行专门测试。我刚在新装的Debian 9.9系统上试了一下，结果一样。
复制步骤：
- ssh -Y remote.host.example.com
- sudo bash
- xset -q > /dev/null 2>&1
完成这 3 个简单步骤后，您可能会看到令人反感的错误消息。
这很容易理解和复制，但有许多活动部分。
我们通过 X 转发 SSH 到远程机器。 这个 ssh 进程必须能够访问本地工作的 X 服务器。 这里我们先讲个笑话 $DISPLAY:
(local) $ DISPLAY=:87 ssh -Y remote
Warning: No xauth data; using fake authentication data for X11 forwarding
Warning 表示 ssh 无法联系本地工作的 X 服务器。
在远程 $DISPLAY 不是:87
(remote) $ echo $DISPLAY
(remote) localhost:11.0
这就是 ssh 的 -Y 的魔力及其 X11 代理的工作原理。
我们 运行 尝试连接到 $DISPLAY 的远程命令：
(remote) $ xset -q
connect /tmp/.X11-unix/X99: No such file or directory
xset: unable to open display "localhost:11.0"
这是你的问题：
(remote) $ xset -q >/dev/null 2>&1
connect /tmp/.X11-unix/X99: No such file or directory
unable 错误消息被 xset 打印出来，
并已被重定向。
但是 connect 错误消息来自 ssh。
请记住 xset 运行s on remote,
而 ssh 在 local.
上 运行ning
您需要在 local before 运行ning ssh[ 上验证 $DISPLAY =63=].
您可以通过多种方式使 ssh 安静下来，
但我不喜欢丢弃错误信息。
一种方法是减少错误的详细程度：
(local) $ DISPLAY=:87 ssh -Y -o LogLevel=FATAL remote 'xset -q &>/dev/null'
有关 ssh 设置的列表，请参阅 man ssh_config。
我想默默地测试X11是否在脚本中工作。
即使我使用（例如）xset q > /dev/null 2>&1
我 strace 了，它似乎不是由 xset 编写的。我也strace了相关的sshd，好像也没有写。
xset、xdpyinfo和How to check if X server is running?处的测试程序都输出了这个无用的错误信息。事实上，vim 也是如此。但是 "ls" 没有。
我也试过：script -e -c 'xset q' /dev/null > /dev/null 2>&1
...但即使这样也会输出错误消息。
我需要做什么来消除这个过于激进的错误消息？
谢谢！
PS: 这是 xset q 的一个 strace:
20878 execve("/usr/bin/xset", ["xset", "q"], 0x7ffe3e91cfe0 /* 33 vars */) = 0
20878 brk(NULL) = 0x563d8a664000
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=141841, ...}) = 0
20878 mmap(NULL, 141841, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f19ac118000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXmuu.so.1", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]p[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=14528, ...}) = 0
20878 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac144000
20878 mmap(NULL, 2109592, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19abd10000
20878 mprotect(0x7f19abd13000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19abf12000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f19abf12000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXext.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]05[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=73640, ...}) = 0
20878 mmap(NULL, 2169496, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19abaf8000
20878 mprotect(0x7f19abb09000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19abd08000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x10000) = 0x7f19abd08000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libX11.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]07[=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=1277384, ...}) = 0
20878 mmap(NULL, 3374392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19ab7c0000
20878 mprotect(0x7f19ab8f3000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19abaf3000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x133000) = 0x7f19abaf3000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]0[=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0755, st_size=2030544, ...}) = 0
20878 mmap(NULL, 4131552, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19ab3c8000
20878 mprotect(0x7f19ab5af000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19ab7af000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1e7000) = 0x7f19ab7af000
20878 mmap(0x7f19ab7b5000, 15072, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19ab7b5000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libxcb.so.1", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P1[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=162232, ...}) = 0
20878 mmap(NULL, 2257576, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19ab1a0000
20878 mprotect(0x7f19ab1c6000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19ab3c6000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x26000) = 0x7f19ab3c6000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=14560, ...}) = 0
20878 mmap(NULL, 2109712, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aaf98000
20878 mprotect(0x7f19aaf9b000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19ab19a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f19ab19a000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXau.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=14456, ...}) = 0
20878 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac142000
20878 mmap(NULL, 2109720, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aad90000
20878 mprotect(0x7f19aad92000, 2097152, PROT_NONE) = 0
20878 mmap(0x7f19aaf92000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f19aaf92000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libXdmcp.so.6", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=22616, ...}) = 0
20878 mmap(NULL, 2117760, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aab88000
20878 mprotect(0x7f19aab8d000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aad8c000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x4000) = 0x7f19aad8c000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libbsd.so.0", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P4[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=80104, ...}) = 0
20878 mmap(NULL, 2179152, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa970000
20878 mprotect(0x7f19aa983000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aab82000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x12000) = 0x7f19aab82000
20878 mmap(0x7f19aab84000, 80, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19aab84000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/librt.so.1", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=][=11=]\"[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=31680, ...}) = 0
20878 mmap(NULL, 2128864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa768000
20878 mprotect(0x7f19aa76f000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aa96e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6000) = 0x7f19aa96e000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]00b[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0755, st_size=144976, ...}) = 0
20878 mmap(NULL, 2221184, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa548000
20878 mprotect(0x7f19aa562000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aa761000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x19000) = 0x7f19aa761000
20878 mmap(0x7f19aa763000, 13440, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19aa763000
20878 close(3) = 0
20878 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac13d000
20878 mmap(NULL, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f19ac115000
20878 arch_prctl(ARCH_SET_FS, 0x7f19ac115740) = 0
20878 mprotect(0x7f19ab7af000, 16384, PROT_READ) = 0
20878 mprotect(0x7f19aa761000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aa96e000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aab82000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aad8c000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19aaf92000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19ab19a000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19ab3c6000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19abaf3000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19abd08000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19abf12000, 4096, PROT_READ) = 0
20878 mprotect(0x563d8872f000, 4096, PROT_READ) = 0
20878 mprotect(0x7f19ac13f000, 4096, PROT_READ) = 0
20878 munmap(0x7f19ac118000, 141841) = 0
20878 set_tid_address(0x7f19ac115a10) = 20878
20878 set_robust_list(0x7f19ac115a20, 24) = 0
20878 rt_sigaction(SIGRTMIN, {sa_handler=0x7f19aa54dcb0, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7f19aa55a890}, NULL, 8) = 0
20878 rt_sigaction(SIGRT_1, {sa_handler=0x7f19aa54dd50, sa_mask=[], sa_flags=SA_RESTORER|SA_RESTART|SA_SIGINFO, sa_restorer=0x7f19aa55a890}, NULL, 8) = 0
20878 rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
20878 prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
20878 brk(NULL) = 0x563d8a664000
20878 brk(0x563d8a685000) = 0x563d8a685000
20878 socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
20878 connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
20878 close(3) = 0
20878 socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
20878 connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
20878 close(3) = 0
20878 openat(AT_FDCWD, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=529, ...}) = 0
20878 read(3, "# /etc/nsswitch.conf\n#\n# Example"..., 4096) = 529
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=304, ...}) = 0
20878 openat(AT_FDCWD, "/etc/host.conf", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
20878 read(3, "# The \"order\" line is only used "..., 4096) = 92
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 futex(0x7f19ab7b7ba4, FUTEX_WAKE_PRIVATE, 2147483647) = 0
20878 openat(AT_FDCWD, "/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=304, ...}) = 0
20878 read(3, "# Dynamic resolv.conf(5) file fo"..., 4096) = 304
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 uname({sysname="Linux", nodename="zareason-limbo", ...}) = 0
20878 openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=141841, ...}) = 0
20878 mmap(NULL, 141841, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f19ac0f0000
20878 close(3) = 0
20878 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
20878 openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = 3
20878 read(3, "7ELF[=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=][=11=]>[=11=][=11=][=11=][=11=]P#[=11=][=11=][=11=][=11=][=11=][=11=]"..., 832) = 832
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=47568, ...}) = 0
20878 mmap(NULL, 2168632, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f19aa330000
20878 mprotect(0x7f19aa33b000, 2093056, PROT_NONE) = 0
20878 mmap(0x7f19aa53a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0xa000) = 0x7f19aa53a000
20878 mmap(0x7f19aa53c000, 22328, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f19aa53c000
20878 close(3) = 0
20878 mprotect(0x7f19aa53a000, 4096, PROT_READ) = 0
20878 munmap(0x7f19ac0f0000, 141841) = 0
20878 openat(AT_FDCWD, "/etc/hosts", O_RDONLY|O_CLOEXEC) = 3
20878 fstat(3, {st_mode=S_IFREG|0644, st_size=403, ...}) = 0
20878 read(3, "127.0.0.1\tlocalhost\n127.0.1.1\tza"..., 4096) = 403
20878 read(3, "", 4096) = 0
20878 close(3) = 0
20878 socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC, IPPROTO_TCP) = 3
20878 setsockopt(3, SOL_TCP, TCP_NODELAY, [1], 4) = 0
20878 setsockopt(3, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
20878 connect(3, {sa_family=AF_INET, sin_port=htons(6013), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
20878 getpeername(3, {sa_family=AF_INET, sin_port=htons(6013), sin_addr=inet_addr("127.0.0.1")}, [124->16]) = 0
20878 uname({sysname="Linux", nodename="zareason-limbo", ...}) = 0
20878 access("/home/dstromberg/.Xauthority", R_OK) = 0
20878 openat(AT_FDCWD, "/home/dstromberg/.Xauthority", O_RDONLY) = 4
20878 fstat(4, {st_mode=S_IFREG|0600, st_size=827, ...}) = 0
20878 read(4, "[=11=][=11=]zareason-limbo[=11=][=11=]10[=11=]MIT-MAGIC"..., 4096) = 827
20878 read(4, "", 4096) = 0
20878 close(4) = 0
20878 getsockname(3, {sa_family=AF_INET, sin_port=htons(37214), sin_addr=inet_addr("127.0.0.1")}, [124->16]) = 0
20878 fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
20878 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
20878 fcntl(3, F_SETFD, FD_CLOEXEC) = 0
20878 poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
20878 writev(3, [{iov_base="l[=11=]\v[=11=][=11=][=11=][=11=][=11=][=11=][=11=]", iov_len=12}, {iov_base="", iov_len=0}, {iov_base="MIT-MAGIC-COOKIE-1", iov_len=18}, {iov_base="[=11=][=11=]", iov_len=2}, {iov_base="6b57f245!H216J", iov_len=16}, {iov_base="", iov_len=0}], 6) = 48
20878 recvfrom(3, 0x563d8a6660e0, 8, 0, NULL, NULL) = -1 EAGAIN (Resource temporarily unavailable)
20878 poll([{fd=3, events=POLLIN}], 1, -1) = 1 ([{fd=3, revents=POLLIN|POLLERR|POLLHUP}])
20878 recvfrom(3, 0x563d8a6660e0, 8, 0, NULL, NULL) = -1 ECONNRESET (Connection reset by peer)
20878 shutdown(3, SHUT_RDWR) = -1 ENOTCONN (Transport endpoint is not connected)
20878 close(3) = 0
20878 write(2, "xset: unable to open display \"l"..., 47) = 47
20878 exit_group(1) = ?
20878 +++ exited with 1 +++
这是一个类型 -a xset:
$ type -a xset
below cmd output started 2019 Sun Jun 30 07:49:33 AM PDT
xset is /usr/bin/xset
运行 没有重定向，显示消息的顺序：
$ xset q
below cmd output started 2019 Sun Jun 30 08:03:24 AM PDT
connect /tmp/.X11-unix/X1: No such file or directory
xset: unable to open display "localhost:13.0"
为了回应 melpomene 的评论，我设置了一个完全没有启动文件的测试帐户。然后我对它进行 ssh -Y，sudo，并得到与上述相同的错误消息。
我一直在 gnome-terminal 中专门测试。我刚刚尝试了 konsole，但再次收到令人讨厌的错误消息。
我刚刚尝试对 openssh 客户端进行 strace；它产生了一次字符串 "connect"，看起来不相关（除了连接到 ssh 服务器）。
我一直在 Linux Mint 19.1 系统上进行专门测试。我刚在新装的Debian 9.9系统上试了一下，结果一样。
复制步骤：
- ssh -Y remote.host.example.com
- sudo bash
- xset -q > /dev/null 2>&1
完成这 3 个简单步骤后，您可能会看到令人反感的错误消息。
这很容易理解和复制，但有许多活动部分。
我们通过 X 转发 SSH 到远程机器。 这个 ssh 进程必须能够访问本地工作的 X 服务器。 这里我们先讲个笑话 $DISPLAY:
(local) $ DISPLAY=:87 ssh -Y remote
Warning: No xauth data; using fake authentication data for X11 forwarding
Warning 表示 ssh 无法联系本地工作的 X 服务器。
在远程 $DISPLAY 不是:87
(remote) $ echo $DISPLAY
(remote) localhost:11.0
这就是 ssh 的 -Y 的魔力及其 X11 代理的工作原理。
我们 运行 尝试连接到 $DISPLAY 的远程命令：
(remote) $ xset -q
connect /tmp/.X11-unix/X99: No such file or directory
xset: unable to open display "localhost:11.0"
这是你的问题：
(remote) $ xset -q >/dev/null 2>&1
connect /tmp/.X11-unix/X99: No such file or directory
unable 错误消息被 xset 打印出来，
并已被重定向。
但是 connect 错误消息来自 ssh。
请记住 xset 运行s on remote,
而 ssh 在 local.
您需要在 local before 运行ning ssh[ 上验证 $DISPLAY =63=].
您可以通过多种方式使 ssh 安静下来， 但我不喜欢丢弃错误信息。 一种方法是减少错误的详细程度：
(local) $ DISPLAY=:87 ssh -Y -o LogLevel=FATAL remote 'xset -q &>/dev/null'
有关 ssh 设置的列表，请参阅 man ssh_config。