linux shell只读变量如何删除

linux shell只读变量如何删除

source /etc/profile 出现 bash:PROMPT-COMMAND: 只读变量
利用unset命令是无法删除只读变量的

如果你linux中没有gdb命令的话，下载一下

sudo yum install gdb

下载好之后

先按照下面的方法试验一下

# readonly test=1
# test=2
bash: test: 只读变量
# cat << EOF| gdb
> attach $$
> call unbind_variable("test")
> detach
> EOF
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-110.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
(gdb) Attaching to process 12409
Reading symbols from /usr/bin/bash...Reading symbols from /usr/bin/bash...(no 	debugging symbols found)...done.
(no debugging symbols found)...done.
Reading symbols from /lib64/libtinfo.so.5...Reading symbols from /lib64/libtinfo.so.5...(no debugging symbols found)...done.
(no debugging symbols found)...done.
Loaded symbols for /lib64/libtinfo.so.5
Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /lib64/libnss_files.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libnss_files.so.2
0x00007fd4b11db17c in waitpid () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install bash-4.2.46-30.el7.x86_64
(gdb) $1 = 0
(gdb) Detaching from program: /usr/bin/bash, process 12409
(gdb) quit

然后对变量进行赋值

test=3

发现没显示只读变量提示，说明已经改好了

那么现在修改PROMPT-COMMAND只读变量属性

 
# cat << EOF| gdb
> attach $$
> call unbind_variable("PROMPT-COMMAND")
> detach
> EOF
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-110.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
(gdb) Attaching to process 12409
Reading symbols from /usr/bin/bash...Reading symbols from /usr/bin/bash...(no 	debugging symbols found)...done.
(no debugging symbols found)...done.
Reading symbols from /lib64/libtinfo.so.5...Reading symbols from /lib64/libtinfo.so.5...(no debugging symbols found)...done.
(no debugging symbols found)...done.
Loaded symbols for /lib64/libtinfo.so.5
Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /lib64/libnss_files.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libnss_files.so.2
0x00007fd4b11db17c in waitpid () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install bash-4.2.46-30.el7.x86_64
(gdb) $1 = 0
(gdb) Detaching from program: /usr/bin/bash, process 12409
(gdb) quit

重新运行一下

source /etc/profile

成功