Dans mon .profile, j'appelle un script pour déterminer la largeur d'une chaîne sur un terminal. Je l'utilise lorsque je me connecte sur la console d'une machine où je ne fais pas confiance à l'ensemble du système LC_CTYPE, ou lorsque je me connecte à distance et que je ne peux pas faire confiance LC_CTYPEpour correspondre au côté distant. Mon script interroge le terminal, plutôt que d'appeler n'importe quelle bibliothèque, car c'était tout l'intérêt de mon cas d'utilisation: déterminer l'encodage du terminal.
Ceci est fragile à plusieurs égards:
- cela modifie l'affichage, donc ce n'est pas une expérience utilisateur très agréable;
- il y a une condition de concurrence si un autre programme affiche quelque chose au mauvais moment;
- il se bloque si le terminal ne répond pas. (Il y a quelques années, j'ai demandé comment améliorer cela , mais cela n'a pas été un gros problème dans la pratique, donc je n'ai jamais pu passer à cette solution. Le seul cas que j'ai rencontré d'un terminal qui ne répond pas était un Windows Emacs accédant à des fichiers distants à partir d'une machine Linux avec la
plinkméthode, et je l'ai résolu en utilisant la plinkxméthode à la place .)
Cela peut ou non correspondre à votre cas d'utilisation.
#! /bin/sh
if [ z"$ZSH_VERSION" = z ]; then :; else
emulate sh 2>/dev/null
fi
set -e
help_and_exit () {
cat <<EOF
Usage: $0 {-NUMBER|TEXT}
Find out the width of TEXT on the terminal.
LIMITATION: this program has been designed to work in an xterm. Only
xterm and sufficiently compatible terminals will work. If you think
this program may be blocked waiting for input from the the terminal,
try entering the characters "0n0n" (digit 0, lowercase letter n,
repeat).
Display TEXT and erase it. Find out the position of the cursor before
and after displaying TEXT so as to compute the width of TEXT. The width
is returned as the exit code of the program. A value of 100 is returned if
the text is wider than 100 columns.
TEXT may contain backslash-escapes: \\0DDD represents the byte whose numeric
value is DDD in octal. Use '\\\\' to include a single backslash character.
You may use -NUMBER instead of TEXT (if TEXT begins with a dash, use
"-- TEXT"). This selects one of the built-in texts that are designed
to discriminate between common encodings. The following table lists
supported values of NUMBER (leftmost column) and the widths of the
sample text in several encodings.
1 ASCII=0 UTF-8=2 latinN=3 8bits=4
EOF
exit
}
builtin_text () {
case $1 in
-*[!0-9]*)
echo 1>&2 "$0: bad number: $1"
exit 119;;
-1) # UTF8: {\'E\'e}; latin1: {\~A\~A\copyright}; ASCII: {}
text='\0303\0211\0303\0251';;
*)
echo 1>&2 "$0: there is no text number $1. Stop."
exit 118;;
esac
}
text=
if [ $# -eq 0 ]; then
help_and_exit 1>&2
fi
case "$1" in
--) shift;;
-h|--help) help_and_exit;;
-[0-9]) builtin_text "$1";;
-*)
echo 1>&2 "$0: unknown option: $1"
exit 119
esac
if [ z"$text" = z ]; then
text="$1"
fi
printf "" # test that it is there (abort on very old systems)
csi='\033['
dsr_cpr="${csi}6n" # Device Status Report --- Report Cursor Position
dsr_ok="${csi}5n" # Device Status Report --- Status Report
stty_save=`stty -g`
if [ z"$stty_save" = z ]; then
echo 1>&2 "$0: \`stty -g' failed ($?)."
exit 3
fi
initial_x=
final_x=
delta_x=
cleanup () {
set +e
# Restore terminal settings
stty "$stty_save"
# Restore cursor position (unless something unexpected happened)
if [ z"$2" = z ]; then
if [ z"$initial_report" = z ]; then :; else
x=`expr "${initial_report}" : "\\(.*\\)0"`
printf "%b" "${csi}${x}H"
fi
fi
if [ z"$1" = z ]; then
# cleanup was called explicitly, so don't exit.
# We use `trap : 0' rather than `trap - 0' because the latter doesn't
# work in older Bourne shells.
trap : 0
return
fi
exit $1
}
trap 'cleanup 120 no' 0
trap 'cleanup 129' 1
trap 'cleanup 130' 2
trap 'cleanup 131' 3
trap 'cleanup 143' 15
stty eol 0 eof n -echo
printf "%b" "$dsr_cpr$dsr_ok"
initial_report=`tr -dc \;0123456789`
# Get the initial cursor position. Time out if the terminal does not reply
# within 1 second. The trick of calling tr and sleep in a pipeline to put
# them in a process group, and using "kill 0" to kill the whole process
# group, was suggested by Stephane Gimenez at
# /unix/10698/timing-out-in-a-shell-script
#trap : 14
#set +e
#initial_report=`sh -c 'ps -t $(tty) -o pid,ppid,pgid,command >/tmp/p;
# { tr -dc \;0123456789 >&3; kill -14 0; } |
# { sleep 1; kill -14 0; }' 3>&1`
#set -e
#initial_report=`{ sleep 1; kill 0; } |
# { tr -dc \;0123456789 </dev/tty; kill 0; }`
if [ z"$initial_report" = z"" ]; then
# We couldn't read the initial cursor position, so abort.
cleanup 120
fi
# Write some text and get the final cursor position.
printf "%b%b" "$text" "$dsr_cpr$dsr_ok"
final_report=`tr -dc \;0123456789`
initial_x=`expr "$initial_report" : "[0-9][0-9]*;\\([0-9][0-9]*\\)0" || test $? -eq 1`
final_x=`expr "$final_report" : "[0-9][0-9]*;\\([0-9][0-9]*\\)0" || test $? -eq 1`
delta_x=`expr "$final_x" - "$initial_x" || test $? -eq 1`
cleanup
# Zsh has function-local EXIT traps, even in sh emulation mode. This
# is a long-standing bug.
trap : 0
if [ $delta_x -gt 100 ]; then
delta_x=100
fi
exit $delta_x
Le script renvoie la largeur dans son état de retour, tronquée à 100. Exemple d'utilisation:
widthof -1
case $? in
0) export LC_CTYPE=C;; # 7-bit charset
2) locale_search .utf8 .UTF-8;; # utf8
3) locale_search .iso88591 .ISO8859-1 .latin1 '';; # 8-bit with nonprintable 128-159, we assume latin1
4) locale_search .iso88591 .ISO8859-1 .latin1 '';; # some full 8-bit charset, we assume latin1
*) export LC_CTYPE=C;; # weird charset
esac