Red Hat Bugzilla – Bug 151485
kill doesn't like 'SIG' prefix in bash scripts invoked through 'sh'
Last modified: 2007-11-30 17:07:17 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.2) Gecko/20030716 Description of problem: Man page states: 'sigspec is either a case-insensitive signal name such as SIGKILL (with or without the SIG prefix)' In an interactive bash, this seems to be true - the following command works: kill -SIGUSR1 1 However, if it is placed in a script: # cat - > /tmp/foo <<EOF > #!/bin/bash > type kill > kill -SIGUSR1 1 > EOF # sh /tmp/foo kill is a shell builtin /tmp/foo: line 3: kill: SIGUSR1: invalid signal specification # Removing the 'SIG' prefix solves the problem. Version-Release number of selected component (if applicable): bash-3.0-19.2 How reproducible: Always Steps to Reproduce: 1. # cat - > /tmp/foo <<EOF > #!/bin/bash > type kill > kill -SIGUSR1 1 > EOF # sh /tmp/foo 2. 3. Actual Results: kill is a shell builtin /tmp/foo: line 3: kill: SIGUSR1: invalid signal specification Expected Results: kill is a shell builtin Additional info: Seems to be related to invoking 'sh'. Invoking 'bash' works: # sh /tmp/foo kill is a shell builtin /tmp/foo: line 3: kill: SIGUSR1: invalid signal specification # bash /tmp/foo kill is a shell builtin # ls -l /bin/sh lrwxrwxrwx 1 root root 4 Mar 3 16:34 /bin/sh -> bash I thought the '#!/bin/bash' would explicitly invoke bash. Same scripts work fine on Enterprise Linux 3 update 4. SELinux is installed. Output from sestatus: # sestatus SELinux status: enabled SELinuxfs mount: /selinux Current mode: enforcing Mode from config file: enforcing Policy version: 18 Policy from config file:targeted Policy booleans: allow_ypbind active dhcpd_disable_trans inactive httpd_disable_trans inactive httpd_enable_cgi active httpd_enable_homedirs active httpd_ssi_exec active httpd_tty_comm inactive httpd_unified active mysqld_disable_trans inactive named_disable_trans inactive named_write_master_zonesinactive nscd_disable_trans inactive ntpd_disable_trans inactive portmap_disable_trans inactive postgresql_disable_transinactive snmpd_disable_trans inactive squid_disable_trans inactive syslogd_disable_trans active winbind_disable_trans inactive ypbind_disable_trans inactive #
The '#!/bin/bash' line is only used when executing the shell script directly, not when the shell script is passed as a parameter to an explicit shell invocation as in 'sh ./script'. The kill built-in command adheres to IEEE Std 1003.1-2001 more strictly when the shell is invoked as 'sh', and so must follow this: Values of signal_name shall be recognized in a case-independent fashion, without the SIG prefix. Allowing the SIG prefix is a bash extension as far as I can tell.