I've tried to run the following bash script:#!/bin/bash                                                                     x=1while [ $x -le 10 ]do    echo Welcome $x times    x = $(( $x + 1))doneAnd when I run it, I get a stream of messages that seem to repeat until I Ctrl-Z it.im4t:test math4tots$ ./mdtest.shWelcome 1 timeslaunch_msg(CheckIn) IPC failure: Operation not permittedXquartz: Unable to locate waiting server: org.x.X11Xquartz: X11.app = /Applications/Utilities/X11.app/Contents/MacOS/X11Xquartz: Starting X server: /Applications/Utilities/X11.app/Contents/MacOS/X11 --listenonlyX11.app: main(): argc=2    argv[0] = /Applications/Utilities/X11.app/Contents/MacOS/X11.bin    argv[1] = --listenonlyWaiting for startup parameters via Mach IPC.X11.app: No launchd socket handed off, unsetting DISPLAYX11.app: do_start_x11_server(): argc=3    argv[0] = x    argv[1] = =    argv[2] = 2Unrecognized option: =use: X [:<display>] [option]-a #                   default pointer acceleration (factor)-ac                    disable access control restrictions-audit int             set audit trail level-auth file             select authorization file-br                    create root window with black background+bs                    enable any backing store support-bs                    disable any backing store support-c                     turns off key-clickc #                    key-click volume (0-100)... Lengthy error message that exceeds 30000 characters ...ttyxx                  server started from init on /dev/ttyxxv                      video blanking for screen-saver-v                     screen-saver without video blanking-wm                    WhenMapped default backing-store-wr                    create root window with white background-maxbigreqsize         set maximal bigrequest size +xinerama              Enable XINERAMA extension-xinerama              Disable XINERAMA extension-dumbSched             Disable smart scheduling, enable old behavior-schedInterval int     Set scheduler interval in msec-sigstop               Enable SIGSTOP based startup+extension name        Enable extension-extension name        Disable extension-query host-name       contact named host for XDMCP-broadcast             broadcast for XDMCP-multicast [addr [hops]] IPv6 multicast for XDMCP-indirect host-name    contact named host for indirect XDMCP-port port-num         UDP port number to send messages to-from local-address    specify the local address to connect from-once                  Terminate server after one session-class display-class   specify display class to send in manage-cookie xdm-auth-bits  specify the magic cookie for XDMCP-displayID display-id  manufacturer display ID for request[+-]accessx [ timeout [ timeout_mask [ feedback [ options_mask] ] ] ]                       enable/disable accessx key sequences-ardelay               set XKB autorepeat delay-arinterval            set XKB autorepeat intervalDevice Dependent Usage:-depth <8,15,24> : use this bit depth.-fakebuttons : fake a three button mouse with Command and Option keys.-nofakebuttons : don't fake a three button mouse.-fakemouse2 <modifiers> : fake middle mouse button with modifier keys.-fakemouse3 <modifiers> : fake right mouse button with modifier keys.  ex: -fakemouse2 option,shift = option-shift-click is middle button.-version : show the server version.Fatal server error:Unrecognized option: (null)   OsVendorFatalError   AbortDDX^Z[1]+  Stopped                 ./mdtest.shI also get a window that flickers (closes and opens repeatedly):Also, in case it is relevant, I'm using Mac OS X Lion, but it doesn't seem like it it should matter...It looked like a harmless enough bash script...
Cryptic Bash Crash
bash
You have an extra space in this line:x = $(( $x + 1))The shell is trying to run the program x, which appears to be an X server (Mac OS's standard file system isn't case sensitive, so I imagine it's actually running X). You need to do this:x=$(( $x + 1))