I programmi che leggono man e info possono processare in modo trasparente pagine compresse con gzip o bzip2, una caratteristica utilizzabile per liberare un po' di spazio sul disco e mantenere allo stesso tempo disponibile la documentazione. Tuttavia le cose non sono così semplici; le directory man tendono a contenere link (hard e simbolici) che non gestiscono semplici idee come le chiamate ricorsive di gzip su di essi. Un modo migliore di agire è usare lo script sottostante.
cat > /usr/sbin/compressdoc << "EOF" #!/bin/bash # VERSION: 20050112.0027 # # Comprime (con bzip2 o gzip) tutte le pagine man in una gerarchia e # aggiorna i link simbolici - By Marc Heerdink <marc @ koelkast.net> # # Modificato per renderlo capace di eseguire opzionalmente gzip o bzip2 # sui file e di trattare appropriatamente tutti i link simbolici # da Mark Hymers <markh @ linuxfromscratch.org> # # Modificato il 30/9/2003 da Yann E. Morin # <yann.morin.1998 @ anciens.enib.fr> per accettare # compressione/decompressione, per gestire correttamente hard-link, # per permettere il cambiamento di hard-link in soft, per specificare # il livello di compressione, per analizzare tutte le occorrenze di # MANPATH in man.conf, per permettere il backup, per permettere di tenere # la versione più recente di una pagina. # # Modificato 20040330 by Tushar Teredesai per sostituire $0 con il nome # dello script. # (Nota: si suppone che lo script sia nel PATH dell'utente) # # Modificato 20050112 by Randy McMurchy per accorciare le linee e # correggere errori grammaticali. # # TODO: # - choose a default compress method to be based on the available # tool : gzip or bzip2; # - offer an option to automagically choose the best compression # methed on a per page basis (eg. check which of # gzip/bzip2/whatever is the most effective, page per page); # - when a MANPATH env var exists, use this instead of /etc/man.conf # (useful for users to (de)compress their man pages; # - offer an option to restore a previous backup; # - add other compression engines (compress, zip, etc?). Needed? # Funny enough, this function prints some help. function help () { if [ -n "$1" ]; then echo "Unknown option : $1" fi ( echo "Usage: $MY_NAME <comp_method> [options] [dirs]" && \ cat << EOT Where comp_method is one of : --gzip, --gz, -g --bzip2, --bz2, -b Compress using gzip or bzip2. --decompress, -d Decompress the man pages. --backup Specify a .tar backup shall be done for all directories. In case a backup already exists, it is saved as .tar.old prior to making the new backup. If a .tar.old backup exists, it is removed prior to saving the backup. In backup mode, no other action is performed. And where options are : -1 to -9, --fast, --best The compression level, as accepted by gzip and bzip2. When not specified, uses the default compression level for the given method (-6 for gzip, and -9 for bzip2). Not used when in backup or decompress modes. --force, -F Force (re-)compression, even if the previous one was the same method. Useful when changing the compression ratio. By default, a page will not be re-compressed if it ends with the same suffix as the method adds (.bz2 for bzip2, .gz for gzip). --soft, -S Change hard-links into soft-links. Use with _caution_ as the first encountered file will be used as a reference. Not used when in backup mode. --hard, -H Change soft-links into hard-links. Not used when in backup mode. --conf=dir, --conf dir Specify the location of man.conf. Defaults to /etc. --verbose, -v Verbose mode, print the name of the directory being processed. Double the flag to turn it even more verbose, and to print the name of the file being processed. --fake, -f Fakes it. Print the actual parameters compman will use. dirs A list of space-separated _absolute_ pathnames to the man directories. When empty, and only then, parse ${MAN_CONF}/man.conf for all occurrences of MANPATH. Nota sulla compressione: C'è stata una discussione su blfs-support sui tassi di compressione sia di gzip che di bzip2 sulle man page, tenendo conto del file system ospitante, l'architettura, ecc... Nel complesso, la conclusione è stata che gzip è molto più efficiente su 'piccoli' file, e bzip2 su 'grandi' file, e piccoli e grandi dipendono molto dai contenuti dei file. Vedere il post originale di Mickael A. Peters, intitolato "Bootable Utility CD", dated 20030409.1816(+0200), e post successivi: http://linuxfromscratch.org/pipermail/blfs-support/2003-April/038817.html Sul mio sistema (x86, ext3), le man page erano 35564KB prima della compressione. gzip -9 le ha compresso fino a 20372KB (57.28%), bzip2 -9 è sceso a 19812KB (55.71%). Che è un 1.57% di guadagno in spazio. Ciò che non è stato preso in considerazione è la velocità di compressione. Ma ha senso? Si ottiene accesso rapido con man page non compresse, o si guadagna spazio al prezzo di un leggero rallentamento. Bene, il mio P4-2.5GHz non mi fa notare la differenza... :-) EOT ) | less } # This function checks that the man page is unique amongst bzip2'd, # gzip'd and uncompressed versions. # $1 the directory in which the file resides # $2 the file name for the man page # Returns 0 (true) if the file is the latest and must be taken care of, # and 1 (false) if the file is not the latest (and has therefore been # deleted). function check_unique () { # NB. When there are hard-links to this file, these are # _not_ deleted. In fact, if there are hard-links, they # all have the same date/time, thus making them ready # for deletion later on. # Build the list of all man pages with the same name DIR=$1 BASENAME=`basename "${2}" .bz2` BASENAME=`basename "${BASENAME}" .gz` GZ_FILE="$BASENAME".gz BZ_FILE="$BASENAME".bz2 # Look for, and keep, the most recent one LATEST=`(cd "$DIR"; ls -1rt "${BASENAME}" "${GZ_FILE}" "${BZ_FILE}" \ 2>/dev/null | tail -n 1)` for i in "${BASENAME}" "${GZ_FILE}" "${BZ_FILE}"; do [ "$LATEST" != "$i" ] && rm -f "$DIR"/"$i" done # In case the specified file was the latest, return 0 [ "$LATEST" = "$2" ] && return 0 # If the file was not the latest, return 1 return 1 } # Name of the script MY_NAME=`basename $0` # OK, parse the command-line for arguments, and initialize to some # sensible state, that is: don't change links state, parse # /etc/man.conf, be most silent, search man.conf in /etc, and don't # force (re-)compression. COMP_METHOD= COMP_SUF= COMP_LVL= FORCE_OPT= LN_OPT= MAN_DIR= VERBOSE_LVL=0 BACKUP=no FAKE=no MAN_CONF=/etc while [ -n "$1" ]; do case $1 in --gzip|--gz|-g) COMP_SUF=.gz COMP_METHOD=$1 shift ;; --bzip2|--bz2|-b) COMP_SUF=.bz2 COMP_METHOD=$1 shift ;; --decompress|-d) COMP_SUF= COMP_LVL= COMP_METHOD=$1 shift ;; -[1-9]|--fast|--best) COMP_LVL=$1 shift ;; --force|-F) FORCE_OPT=-F shift ;; --soft|-S) LN_OPT=-S shift ;; --hard|-H) LN_OPT=-H shift ;; --conf=*) MAN_CONF=`echo $1 | cut -d '=' -f2-` shift ;; --conf) MAN_CONF="$2" shift 2 ;; --verbose|-v) let VERBOSE_LVL++ shift ;; --backup) BACKUP=yes shift ;; --fake|-f) FAKE=yes shift ;; --help|-h) help exit 0 ;; /*) MAN_DIR="${MAN_DIR} ${1}" shift ;; -*) help $1 exit 1 ;; *) echo "\"$1\" is not an absolute path name" exit 1 ;; esac done # Redirections case $VERBOSE_LVL in 0) # O, be silent DEST_FD0=/dev/null DEST_FD1=/dev/null VERBOSE_OPT= ;; 1) # 1, be a bit verbose DEST_FD0=/dev/stdout DEST_FD1=/dev/null VERBOSE_OPT=-v ;; *) # 2 and above, be most verbose DEST_FD0=/dev/stdout DEST_FD1=/dev/stdout VERBOSE_OPT="-v -v" ;; esac # Note: on my machine, 'man --path' gives /usr/share/man twice, once # with a trailing '/', once without. if [ -z "$MAN_DIR" ]; then MAN_DIR=`man --path -C "$MAN_CONF"/man.conf \ | sed 's/:/\\n/g' \ | while read foo; do dirname "$foo"/.; done \ | sort -u \ | while read bar; do echo -n "$bar "; done` fi # If no MANPATH in ${MAN_CONF}/man.conf, abort as well if [ -z "$MAN_DIR" ]; then echo "No directory specified, and no directory found with \`man --path'" exit 1 fi # Fake? if [ "$FAKE" != "no" ]; then echo "Actual parameters used:" echo -n "Compression.......: " case $COMP_METHOD in --bzip2|--bz2|-b) echo -n "bzip2";; --gzip|__gz|-g) echo -n "gzip";; --decompress|-d) echo -n "decompressing";; *) echo -n "unknown";; esac echo " ($COMP_METHOD)" echo "Compression level.: $COMP_LVL" echo "Compression suffix: $COMP_SUF" echo -n "Force compression.: " [ "foo$FORCE_OPT" = "foo-F" ] && echo "yes" || echo "no" echo "man.conf is.......: ${MAN_CONF}/man.conf" echo -n "Hard-links........: " [ "foo$LN_OPT" = "foo-S" ] && echo "convert to soft-links" || echo "leave as is" echo -n "Soft-links........: " [ "foo$LN_OPT" = "foo-H" ] && echo "convert to hard-links" || echo "leave as is" echo "Backup............: $BACKUP" echo "Faking (yes!).....: $FAKE" echo "Directories.......: $MAN_DIR" echo "Verbosity level...: $VERBOSE_LVL" exit 0 fi # If no method was specified, print help if [ -z "${COMP_METHOD}" -a "${BACKUP}" = "no" ]; then help exit 1 fi # In backup mode, do the backup solely if [ "$BACKUP" = "yes" ]; then for DIR in $MAN_DIR; do cd "${DIR}/.." DIR_NAME=`basename "${DIR}"` echo "Backing up $DIR..." > $DEST_FD0 [ -f "${DIR_NAME}.tar.old" ] && rm -f "${DIR_NAME}.tar.old" [ -f "${DIR_NAME}.tar" ] && mv "${DIR_NAME}.tar" "${DIR_NAME}.tar.old" tar -cfv "${DIR_NAME}.tar" "${DIR_NAME}" > $DEST_FD1 done exit 0 fi # I know MAN_DIR has only absolute path names # I need to take into account the localized man, so I'm going recursive for DIR in $MAN_DIR; do MEM_DIR=`pwd` cd "$DIR" for FILE in *; do # Fixes the case were the directory is empty if [ "foo$FILE" = "foo*" ]; then continue; fi # Fixes the case when hard-links see their compression scheme change # (from not compressed to compressed, or from bz2 to gz, or from gz # to bz2) # Also fixes the case when multiple version of the page are present, # which are either compressed or not. if [ ! -L "$FILE" -a ! -e "$FILE" ]; then continue; fi # Do not compress whatis files if [ "$FILE" = "whatis" ]; then continue; fi if [ -d "$FILE" ]; then cd "${MEM_DIR}" # Go back to where we ran "$0", # in case "$0"=="./compressdoc" ... # We are going recursive to that directory echo "-> Entering ${DIR}/${FILE}..." > $DEST_FD0 # I need not pass --conf, as I specify the directory to work on # But I need exit in case of error "$MY_NAME" ${COMP_METHOD} ${COMP_LVL} ${LN_OPT} ${VERBOSE_OPT} \ ${FORCE_OPT} "${DIR}/${FILE}" || exit 1 echo "<- Leaving ${DIR}/${FILE}." > $DEST_FD1 cd "$DIR" # Needed for the next iteration of the loop else # !dir if ! check_unique "$DIR" "$FILE"; then continue; fi # Check if the file is already compressed with the specified method BASE_FILE=`basename "$FILE" .gz` BASE_FILE=`basename "$BASE_FILE" .bz2` if [ "${FILE}" = "${BASE_FILE}${COMP_SUF}" \ -a "foo${FORCE_OPT}" = "foo" ]; then continue; fi # If we have a symlink if [ -h "$FILE" ]; then case "$FILE" in *.bz2) EXT=bz2 ;; *.gz) EXT=gz ;; *) EXT=none ;; esac if [ ! "$EXT" = "none" ]; then LINK=`ls -l "$FILE" | cut -d ">" -f2 \ | tr -d " " | sed s/\.$EXT$//` NEWNAME=`echo "$FILE" | sed s/\.$EXT$//` mv "$FILE" "$NEWNAME" FILE="$NEWNAME" else LINK=`ls -l "$FILE" | cut -d ">" -f2 | tr -d " "` fi if [ "$LN_OPT" = "-H" ]; then # Change this soft-link into a hard- one rm -f "$FILE" && ln "${LINK}$COMP_SUF" "${FILE}$COMP_SUF" chmod --reference "${LINK}$COMP_SUF" "${FILE}$COMP_SUF" else # Keep this soft-link a soft- one. rm -f "$FILE" && ln -s "${LINK}$COMP_SUF" "${FILE}$COMP_SUF" fi echo "Relinked $FILE" > $DEST_FD1 # else if we have a plain file elif [ -f "$FILE" ]; then # Take care of hard-links: build the list of files hard-linked # to the one we are {de,}compressing. # NB. This is not optimum has the file will eventually be # compressed as many times it has hard-links. But for now, # that's the safe way. inode=`ls -li "$FILE" | awk '{print $1}'` HLINKS=`find . \! -name "$FILE" -inum $inode` if [ -n "$HLINKS" ]; then # We have hard-links! Remove them now. for i in $HLINKS; do rm -f "$i"; done fi # Now take care of the file that has no hard-link # We do decompress first to re-compress with the selected # compression ratio later on... case "$FILE" in *.bz2) bunzip2 $FILE FILE=`basename "$FILE" .bz2` ;; *.gz) gunzip $FILE FILE=`basename "$FILE" .gz` ;; esac # Compress the file with the given compression ratio, if needed case $COMP_SUF in *bz2) bzip2 ${COMP_LVL} "$FILE" && chmod 644 "${FILE}${COMP_SUF}" echo "Compressed $FILE" > $DEST_FD1 ;; *gz) gzip ${COMP_LVL} "$FILE" && chmod 644 "${FILE}${COMP_SUF}" echo "Compressed $FILE" > $DEST_FD1 ;; *) echo "Uncompressed $FILE" > $DEST_FD1 ;; esac # If the file had hard-links, recreate those (either hard or soft) if [ -n "$HLINKS" ]; then for i in $HLINKS; do NEWFILE=`echo "$i" | sed s/\.gz$// | sed s/\.bz2$//` if [ "$LN_OPT" = "-S" ]; then # Make this hard-link a soft- one ln -s "${FILE}$COMP_SUF" "${NEWFILE}$COMP_SUF" else # Keep the hard-link a hard- one ln "${FILE}$COMP_SUF" "${NEWFILE}$COMP_SUF" fi # Really work only for hard-links. Harmless for soft-links chmod 644 "${NEWFILE}$COMP_SUF" done fi else # There is a problem when we get neither a symlink nor a plain # file. Obviously, we shall never ever come here... :-( echo -n "Whaooo... \"${DIR}/${FILE}\" is neither a symlink " echo "nor a plain file. Please check:" ls -l "${DIR}/${FILE}" exit 1 fi fi done # for FILE done # for DIR EOF chmod 755 /usr/sbin/compressdoc
Ora, come utente root, si può digitare compressdoc --bz2 per comprimere tutte le pagine man del proprio sistema. Si può anche eseguire compressdoc --help per avere un help completo su cosa lo script è capace di fare.
Non dimenticare che alcuni programmi, come il sistema X Window e XEmacs, installano anche la propria documentazione in posti non standard (come /usr/X11R6/man, ecc.). Assicurarsi di aggiungere queste locazioni al file /etc/man.conf, come sezione MANPATH=[/path].
Esempio:
...
MANPATH=/usr/share/man
MANPATH=/usr/local/man
MANPATH=/usr/X11R6/man
MANPATH=/opt/qt/doc/man
...
Generalmente i sistemi di installazione dei pacchetti non comprimono pagine man/info, il che significa che sarà necessario eseguire di nuovo lo script se si vogliono mantenere le dimensioni della propria documentazione più piccole possibile. Inoltre notare che l'esecuzione dello script dopo l'aggiornamento di un pacchetto è sicura; quando si hanno numerose versioni di una pagina (per esempio una compressa e una non compressa) la più recente è mantenuta e le altre vengono cancellate.
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