In util-linux2.25, the "column" command isn't written for Linux using a
Linux-console (among others). It assumes 8-column
fixed-width tabs and screen width of 80).
The Linux-console (or any emulator) and terminals supporting
the EMCA-48 standard (vt-100-emulating terms, as well as "xterm")
can have tabs set to arbitrary spacing.
Attached is a bash-script that can show current tab settings
as well as set them to a new value.
It only supports setting tabs to fixed-width, but there is nothing
preventing tabs from being set to variable width expansions.
Ex:
tty_tab 8
tty_tab
(from 1, tabs skip to column: 9 17 25 33 41 49 57 65 73 80
tty_tab 2
tty_tab
(from 1, tabs skip to column: 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31
33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 80
Suggestions to fix column (or other progs that deal
w/the console and use tabs):
1) allow -i (-t is taken) to specify width of terminal tab expansion
-i 8 (default)
-i 4 (some like 4-column indents)
-i 2 (and some use 2 to keep down line length). I've seen "1" used
as a tabsize in javascript files...
1a) (low priority) -- have "-i" take a list of numbers, like
-i 18 36 44 54
(might be reasonable for /etc/fstab?) -- any tabs beyond the
last would use the last specified interval (in above case, "10")
2) --no-tabs
A "Don't use tabs" option for lining up columns, use spaces.
AFAIK, spaces are a fixed size on tty's.
----
There's a tab-set program in the ncurses-utils as well called 'tabs'.
#!/bin/bash -u
#console_codes(4) man page... vt100/2 et && EMCA-48 standard
# (c) la walsh (2013) -- free to use and modify for personal use.
# -- optionally licenced under Gnu v3 license.
# v0.0.3 - try to reduce tabcols to minimal set to reproduce.
# v0.0.2 - set tabs for full terminal width (try to get term width)
shopt -s expand_aliases extglob
alias my=declare sub=function
alias int='my -i' array='my -a' intArray='my -ia' string=my
my _Pt=$(type -t P)
[[ $_Pt && $_Pt == function ]] && unset -f P
alias P=printf
unset _Pt
P -v clrallts "\x1b[3g"
P -v sts "\033H"
P -v cpr "\x1b[6n"
sub getcols() {
local sttyout="$(stty size </dev/tty)"
int default_cols=80
if [[ -n ${COLUMNS:-""} && $COLUMNS =~ ^[0-9]+$ ]]; then
default_cols=$COLUMNS; fi
[[ -z ${sttyout:-""} ]] && { echo $default_cols; return 0; }
int cols="${sttyout#*\ }"
echo -n $[cols<2?default_cols:cols]
return 0
}
sub getpos () {
string ans wanted=${1:-xy}
int attempt=0 max_attempt=1 # in case of rare failure case
# use 'attempt' value as additional
# time to wait for response
while : ; do
( ( P "\x1b[6n" >/dev/tty) & 2>/dev/null )
read -sd R -r -t $[2 + attempt] ans </dev/tty;
ans=${ans:2};
int x=0-1 y=0-1
if ! x="${ans#*;}" y="${ans%;*}" 2>/dev/null ||
((x==-1||y==-1)); then
((attempt+=1 < max_attempt)) && continue
fi
break; done
string out=""
[[ $wanted =~ x ]] && out="$x"
[[ $wanted =~ y ]] && out="${out:+$x }$y"
[[ $out ]] && echo -n "$out"
}
declare -ia tabs
sub get_tabs () {
P "\r"
tabs=()
int pos=0 oldpos=0-1
while ((oldpos!=pos));do
((pos)) && tabs+=($pos)
oldpos=pos
P "\t"
pos=$(getpos x)
done
P "\r"
return 0
}
# Note: this sub uses ability to _read_ tabstops as _proxy_ for setting them
# (i.e. it makes no sense to be able to read them if you can't set them)
sub test_tabset_ability () {
string prompt="tty_tab:"
int newcol=${#prompt}+1
P "\r$prompt"
int mycol=$(getpos x)
((mycol && mycol==newcol)) && return 0 ## return OK
{ P " Term tabset ability not detected mycol=${mycol:-''},"
P " promptlen=$newcol)\n"; } >&2
exit -1
}
sub do_help_n_display_curtabs () {
P " <n> - set tab stop to N\r"
intArray diffs;
int last=1 cur i
string eol=""
get_tabs && {
for ((i=0; i<${#tabs[@]}; ++i)); do
cur=${tabs[i]}
diffs[i]=cur-last
last=cur
done
intArray reverse_tabs_set=()
int prevtab=0-1
for ((i=${#diffs[@]}-2; i>0; --i)); do
int thistab=${diffs[i]}
if ((thistab!= prevtab)) ;then
reverse_tabs_set+=($thistab)
prevtab=thistab
fi
done
P "current value: tty_tab "
for ((i=${#reverse_tabs_set[@]}-1; i>=0; --i)); do
P "%d " "${reverse_tabs_set[i]}"; done
P "\r";
}
get_tabs && {
P "(from 1, tabs skip to column: "
P "%s " "${tabs[@]}"
P "\r\n"
}
}
sub set_tabs () {
int max_col=${1:=0-80}
int tabstop=${2:-?"need a param for tabstop"}
int tab=$tabstop pos=0
string str=""
P $clrallts ## reset old tabs
while ((++pos<cols)) ;do ## move across screen setting tabs
str+=" "
((pos%tab)) || str+="$sts"
done
P "\r$str\r"
}
int cols=$(getcols)
test_tabset_ability ## exits if no ability
if (($#==0)) ; then
do_help_n_display_curtabs
exit 1
else
set_tabs "$cols" "$@"
fi
# vim: ts=2 sw=2
