source: chapter08/strippingagain.xml@ b8d5542

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
  %general-entities;
]>

<sect1 id="ch-system-strippingagain">
  <?dbhtml filename="strippingagain.html"?>

  <title>Stripping Again</title>

  <para>This section is optional.  If the intended user is not a 
  programmer and does not plan to do
  any debugging on the system software, the system size can be decreased
  by about 2 GB by removing the debugging symbols from binaries and
  libraries. This causes no inconvenience other than not being able to
  debug the software fully anymore.</para>

  <para>Most people who use the commands mentioned below do not
  experience any difficulties. However, it is easy to make a typo and
  render the new system unusable, so before running the
  <command>strip</command> commands, it is a good idea to make a
  backup of the LFS system in its current state.</para>

  <para>The debugging symbols for selected libraries are placed
  in separate files.  This debugging information is needed if running 
  regression tests that use <ulink 
  url='&blfs-book;/general/valgrind.html'>valgrind</ulink> or <ulink 
  url='&blfs-book;/general/gdb.html'>gdb</ulink> later in BLFS.
  </para>

  <para>Note that <command>strip</command> will overwrite the binary or library
  file it is processing.  This may crash the processes using code or data from
  the file.  If the process running <command>strip</command> itself is
  affected, the binary or library being stripped may be destroyed.  This may
  make the system completely unusable.  To avoid it, we'll copy some libraries
  and binaries into <filename class="directory">/tmp</filename>, strip them
  there, and install them back with the <command>install</command> command.
  Read the related entry in <xref linkend="pkgmgmt-upgrade-issues"/> for the
  rationale to use the <command>install</command> command here.</para>

  <note><para>The ELF loader's name is ld-linux-x86-64.so.2 on 64-bit systems
  and ld-linux.so.2 on 32-bit systems.  The contruct below selects the 
  correct name for the current architecture.</para></note>


<!-- also of interest are libgfortan, libgo, libgomp, and libobjc from GCC -->

<!--<screen><userinput>save_lib="ld-2.25.so libc-2.25.so libpthread-2.25.so libthread_db-1.0.so"-->
      <screen><userinput>save_usrlib="$(cd /usr/lib; ls ld_linux*)
             libc.so.6
             libthread_db.so.1
             libquadmath.so.&libquadmath-version; 
             libstdc++.so.&libstdcpp-version;
             libitm.so.&libitm-version; 
             libatomic.so.&libatomic-version;" 

cd /usr/lib
for LIB in $save_usrlib; do
    objcopy --only-keep-debug $LIB $LIB.dbg
    cp $LIB /tmp/$LIB
    strip --strip-unneeded /tmp/$LIB
    objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
    install -vm755 /tmp/$LIB /usr/lib
    rm /tmp/$LIB
done</userinput>
<userinput arch="ml_32,ml_all">
cd /usr/lib32
for LIB in $save_usrlib; do
    objcopy --only-keep-debug $LIB $LIB.dbg
    cp $LIB /tmp/$LIB
    strip --strip-unneeded /tmp/$LIB
    objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
    install -vm755 /tmp/$LIB /usr/lib32
    rm /tmp/$LIB
done</userinput>
<userinput arch="ml_x32,ml_all">
cd /usr/libx32
for LIB in $save_usrlib; do
    objcopy --only-keep-debug $LIB $LIB.dbg
    cp $LIB /tmp/$LIB
    strip --strip-unneeded /tmp/$LIB
    objcopy --add-gnu-debuglink=$LIB.dbg /tmp/$LIB
    install -vm755 /tmp/$LIB /usr/libx32
    rm /tmp/$LIB
done</userinput><userinput>

online_usrbin="bash find strip"
online_usrlib="libbfd-&binutils-version;.so
               libhistory.so.&readline-version;
               libncursesw.so.&ncurses-version;
               libm.so.6
               libreadline.so.&readline-version;
               libz.so.&zlib-version;
               $(cd /usr/lib; find libnss*.so* -type f)"

for BIN in $online_usrbin; do
    cp /usr/bin/$BIN /tmp/$BIN
    strip --strip-unneeded /tmp/$BIN
    install -vm755 /tmp/$BIN /usr/bin
    rm /tmp/$BIN
done

for LIB in $online_usrlib; do
    cp /usr/lib/$LIB /tmp/$LIB
    strip --strip-unneeded /tmp/$LIB
    install -vm755 /tmp/$LIB /usr/lib
    rm /tmp/$LIB
done</userinput><userinput arch="ml_32,ml_all">
for LIB in $online_usrlib; do
    cp /usr/lib32/$LIB /tmp/$LIB
    strip --strip-unneeded /tmp/$LIB
    install -vm755 /tmp/$LIB /usr/lib32
    rm /tmp/$LIB
done</userinput><userinput arch="ml_x32,ml_all">
for LIB in $online_usrlib; do
    cp /usr/libx32/$LIB /tmp/$LIB
    strip --strip-unneeded /tmp/$LIB
    install -vm755 /tmp/$LIB /usr/libx32
    rm /tmp/$LIB
done</userinput><userinput>

for i in $(find /usr/lib -type f -name \*.so* ! -name \*dbg) \
         $(find /usr/lib -type f -name \*.a)                 \
         $(find /usr/{bin,sbin,libexec} -type f); do
    case "$online_usrbin $online_usrlib $save_usrlib" in
        *$(basename $i)* ) 
            ;;
        * ) strip --strip-unneeded $i 
            ;;
    esac
done</userinput><userinput arch="ml_32,ml_all">
for i in $(find /usr/lib32 -type f -name \*.so* ! -name \*dbg); do
    case "$online_usrlib $save_usrlib" in
        *$(basename $i)* )
            ;;
        * ) strip --strip-unneeded $i
            ;;
    esac
done</userinput><userinput arch="ml_x32,ml_all">
for i in $(find /usr/libx32 -type f -name \*.so* ! -name \*dbg); do
    case "$online_usrlib $save_usrlib" in
        *$(basename $i)* )
            ;;
        * ) strip --strip-unneeded $i
            ;;
    esac
done</userinput><userinput>

unset BIN LIB save_usrlib online_usrbin online_usrlib
</userinput></screen>

  <para>A large number of files will be reported as having their file
  format not recognized. These warnings can be safely ignored. These
  warnings indicate that those files are scripts instead of
  binaries.</para>

</sect1>