[ -e "foo" -o -L "foo" -a ! -e "foo" ]
it has no sense doing twice the "-e" test
$ ln -s nonexistent foo
$ [ -e "foo" -o -L "foo" -a ! -e "foo" ] && echo ok || echo ko
ok
$ [ -e "foo" -o -L "foo" ] && echo ok || echo ko
ok
as you can see, the first "-e" check imply the second one
(aka, if
is_file()
{
[ -f "$1" ]
}
is_file /path/to/dir/* || echo empty
test is redundant too
---
this could be another way to accomplish this
empty_dir() {
eval test \" $1/* \" == \"" $1/* "\";
}
(excluding invisible files...)
is_file()
{
[ -f "$1" ] && return
return 1
}
is_file /path/to/dir/* || echo empty
you don't need to check more than the first element
Юрий Пухальский wrote:
Good day!
Theres is a problem with a following code:
echo a:b|IFS=: read a b; echo $a
this seems work
$ echo "a:b" | { IFS=":" read a b; echo $a; }
a
Gerard wrote:
I apologize for asking what is probably a dumb question, but where can
I find a definitive listing of what features are available in each
version of Bash.
For example, I only have access to Bash-4 on my system. I need to know
if " $(< " also works on Bash < 4. I also have a few que
Based on your question, I'm guessing you're in bash 3.2 or earlier, where
$ echo $BASH_VERSION
3.2.39(1)-release
$ cat /etc/issue
Debian GNU/Linux 5.0 \n \l
your "hd <(echo -en \\0{0..3}{0..7}{0..7})" is expanded as if you had typed
"hd <(echo -en \\) <(echo -en \\0001) <(echo -en \\000
Also perhaps indicate what you want to achieve (I don't have an
hd command, and didn't find a man page after a quick search)
sorry.. i'll be more precise in future...
but, if you don't have hd (hexdump) how can you see the content of a,
for example, strange file
i mean
$ ls -l
total 0
-rw-r
$ hd <(echo -en \\0{0..3}{0..7}{0..7})
it breaks the console.
The answer is in the part you neglected to read.
NULL can be passed to function only "escaped"
\0
\x00
but $'\x00' is not like "\x00", because the first is expanded "before",
and the second is expanded "after"
$ printf $'\x00'
+-+-+-+-+-+-+--+ +--+--+
|p|r|i|n|t|f|\0| |\0|\0|
+-+-+-+-+-
When you run read -d $'\x00' what you're really doing is setting up
a bunch of C-strings in memory like this:
+-+-+-+-+--+-
|r|e|a|d|\0|
+-+-+-+-+--+-
+-+-+--+-
|-|d|\0|
+-+-+--+-
+--+--+-
|\0|\0|
+--+--+-
WOW!
but...
$ printf one$'\x00'two\\n
+-+-+-+-+-+-+--+
|p|r|i|n|t|f|\0|
$ printf "\x00\n" | cat -A
^@
it works, so why...
$ printf $'\x00' | cat -A
$
... not?
(Note blank line in the output -- one newline from the echo command,
and one from the actual content of $myvar.) Using printf -v instead of
x=$(printf) means you don't suffer from the trailing-newline-removal
that command substitution does.
I'm a bit puzzled by the original e-mail, though. I do
it sounds strange, beacuse
$ find . -print0 | while read -d $'\x00'; do touch "$REPLY"; done
works fine.
but if I try to "output" $'\x00', I can't.
Hi, I'm using older bash 3.2.39, so please forgiveme if in your newer
bash this issue does not arise.
0x00 and 0x0a has no output in printf "%q"
$ for i in {0..9} a; do printf "%q\n" "`echo -en \"\x0$i\"`"; done
''
$'\001'
$'\002'
$'\003'
$'\004'
$'\005'
$'\006'
$'\a'
$'\b'
$'\t'
''
-
http://www.opengroup.org/onlinepubs/9699919799/utilities/printf.html#tag_20_94
(ouch!)
ok!
thanks!
I'm on error, I know... but, in your bash-ref guide you don't explain a
lot printf
and in man printf don't do it too...
from man printf
-
NOTE: your shell may have its own version of printf, which usually
supersedes the version described here. Please refer to your s
what's the rasonable limit in using this "compact" contruct, after which
the for (( i=0; i<1000...; i++ )) became better?
There's nothing to fix. It might help if you provide some markers
sorry, and thanks for your patience...
in your test patterns so you can see where each argument begins and
ends, e.g.,
$ printf "(%d) {%s}\n" 1 ok -
(1) {ok}
-bash: printf: -: invalid number
(0) {}
... and f
$ printf "%s\n" ok -
ok
-
why that score in the newline?
$ printf "%d %s\n" 1 ok -
1 ok
-bash: printf: -: invalid number
0
why getting error here, and not in the previous?
why "invalid number" ?
what is that zero?
$ printf "%2s\n" qwerty
qwerty
strings larger than fixed-wi
using ^V to pass an ascii character to read, the behavior is incoherent
beetween simple read, and read -nx
$ read
^V^A
$ hd <(echo -n $REPLY)
01|.|
0001
$ read -n1
^V
$ hd <(echo -n $REPLY)
16
this command should starts the graphic character set (to create masks)
$ tput smacs
but, using aterm or Eterm, it does not work
but it works using this form (lieing...)
$ TERM=xterm tput smacs
does anyone know where is the problem?
Yes, it's ok. Posix says that printf field widths are specified in number
of bytes.
I've never red nothing about POSIX, but imho, in the past, "char" and
"byte" was synonymous
maybe last POSIX definitions are very old...
hi
thanks for your helps...
I have written some code to create mixed dialog boxes, using a way
roughly like object-oriented, i.e. using objects, properties and events.
may be it can be useful to someone
you can "take a look" using this link:
http://www.webalice.it/antonio_macchi/sourcedialog.
Antonio Macchi wrote:
thanks... but parameters expansions and printf builtin works differently
about it...
same problem with read...
LC_CTYPE="en_US.UTF-8"
$ read -n1
è
$ hexdump -C <(echo -n $REPLY)
c3|.|
0
thanks... but parameters expansions and printf builtin works differently
about it...
$ locale | grep LC_CTYPE
LC_CTYPE="en_US.UTF-8"
$ a=eèèèe
$ b=e
$ echo ${#a}
5
$ echo ${#b}
5
$ printf "*%-10s*" $a
*eèèèe *
$ printf "*%-10s*" $b
*e *
is it ok?
Antonio Macchi wrote:
$ a=$'\xd9\xbf'
$ echo ${#a}
1
$ a2=${a:0:1}
$ echo ${#a2}
1
ops... I mean...
$ a2=${a:0:1}
$ hexdump -C <(echo $a2)
d9 bf 0a |...|
0003
seems bash can't break this two characters...
$ a=$'\xd9\xbf'
$ echo ${#a}
1
$ a2=${a:0:1}
$ echo ${#a2}
1
this two characters are "j" and "k" graphical characters in linux
terminal/console
I need to extract only one... but apparently I can't.
And for the same reason some people hardcode the dot or the comma as
thousands separator in their code, ignoring locale settings. "Never seen
something different."
what's the best?
hardcoding, improving efficiency, and putting another brick on the wall
of standardization..
...or i18n/TERM
commands like "ls --color" does not use terminfo capabilities...
...use instead fixed strings (without regards about TERMinal)
is this a good (and safe) choice too?
IMHO not. Too many assumptions. GNU ls seems to always assume an ANSI
terminal, regardless which TERM is set. Or did I miss some
Start at
http://bash-hackers.org/wiki/doku.php/scripting/terminalcodes
commands like "ls --color" does not use terminfo capabilities...
$ hexdump -c <(TERM=xterm ls -d / --color=always)
000 033 [ 0 0 m 033 [ 0 1 ; 3 4 m / 033 [
010 0 0 m \n 033 [ m
The environment is designed to be inherited.
The subshell even inherits the shell variables.
I 'm not sure what causes you trouble here or what it could be incoherent with?
i think that
$ ( echo $x )
is like
$ bash -c 'echo $x'
I'm on error... but I can't understand why
$ declare +x x
$ x=one
$ ( echo $x; x=two; echo $x )
one
two
subshell inherits "x"?
is this behavior coherent?
$ a=ok
$ b=a
$ echo ${!b-a}
ok
$ unset b
$ echo ${!b-a}
a
imho, the last command should expand to "ok" too
trap trapfunc SIGWINCH
trapfunc () {
for i in {1..1000}; do
tput cup 0 0
echo OK
done
}
I have used one thousand echoes only to assure error raising every time.
But you can use one hundred instead, and you will see the error raise
more rarely
Probably error raise (very very rare
If I run this script in xterm, and I maximize (not resize) the window,
I'll get (nearly always) a very strange error... something like
./test: line 17: wait_for: No record of process 22659
but if I use 'read' without timing or with a very long time ( -t10 ) the
error does not raise.
---
$ a=OUTSIDE
$ f1 () { local a=INSIDE; f2; }
$ f2 () { echo "before: $a";
unset a;
echo "after: $a"; }
$ f3 () { local a=INSIDE;
echo "before: $a";
unset a;
echo "after: $a"; }
$ f1
before: INSIDE
after: OUTSIDE
$ f3
before: INSIDE
after:
I
$ a=( $'\x7e' $'\x7f' $'\x80' )
$ hexdump -C <(echo -n [EMAIL PROTECTED] )
7e 20 01 7f 20 80 |~ .. .|
0006
bash puts two characters (\x01 and \x7f) instead of only one \x7f
but...
$ a[1]=$'\x7f'
$ hexdump -C <(echo -n [EMAIL PROTECTED] )
0
#!/bin/bash -e
trap "rm test_fifo" 0
mkfifo test_fifo
ls / > test_fifo &
exec 9<&0
while read dirname
do
echo $dirname
# if I wait, exits!!!
read -t 2 -p "press enter..." 0<&9
done < test_fifo
exec 9<&-
exit 0
Here you are:
mercurius:/usr/src/BadPenguin# cat bash-3.2-dietlibc.unified-patch
--- build/bash-3.2/lib/sh/winsize.c.orig2006-07-28
05:57:45.0 +0200
+++ build/bash-3.2/lib/sh/winsize.c 2008-09-03 14:56:46.0 +0200
@@ -43,6 +43,11 @@
#include
+/* Antonio Gallo
#!/bin/bash
a=( 1 2 3 )
b=( 4 5 6 )
x=a
eval b=( [EMAIL PROTECTED] )
echo [EMAIL PROTECTED]
#output:
#1 2 3
x=b
eval $x=( [EMAIL PROTECTED] )
#output:
#./tst: line 15: syntax error near unexpected token `('
#./tst: line 15: `eval $x=( [EMAIL PROTECTED] ) '
read -t0 actually does nothing
may be, could be used for -flushing pre-entered-key-buffer-
while true
do
read -s -n1 -t0 x
test $x && break
echo "loop"
done
Description:
it's not a bug, but a strange behavior
the flag interactive_comments is accessible from both shopt and shopt -o
shopt | grep interactive_comments
shopt -o | grep interactive_comments
in your documentation (bashref), shopt -o (set -o) does not have this
flag...
thanks for y
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