bash true/false redirection error

On bash 4.2.8(1)-release (x86_64-pc-linux-gnu) on Ubuntu 11.04 this command

[ $(wc -l /var/w开发者_StackOverflow社区ww/some.log|cut -d " " -f 1) -le 6 ] || echo "no"

yields

 echo: command not found

for as long as the || clause would come into affect. The && clause is working. I have tried changing the order (|| first, && first) to no avail.

Funny things is,

true && echo "yes" || echo "no"

yields

yes

and

false && echo "yes" || echo "no"

yields

no

so I suppose something is wrong with my test-clause. I'd like to check if the file length of some.log is less or equal to 6, if not then do something else then if yes.

Double brackets in the test-clause don't not work, either.

The long-form of test does work, though:

test $(wc -l /var/www/some.log|cut -d " " -f 1) -le 6 && echo "yes" || echo "no"
yes

Funny, huh?

As always, thank you for any tips/hints on this.

Christian.

Try this (with 2 [ and ]):

[[ $(wc -l /var/www/some.log|cut -d " " -f 1) -le 6 ]] || echo "no"
^^                                                  ^^

From the bash's man:

Compound Commands

...

[[ expression ]]

Return a status of 0 or 1 depending on the evaluation of the conditional expression expression. Expressions are composed of the primaries described below under CONDITIONAL EXPRESSIONS.

I guess the single [ and ] is not a standard was of performing tests, even if it works on my side.

Edit:

Actually, [ and ] are a standard way of doing tests, it is a buildin command in bash. If [[ ... ]] works and [ ... ] is not working, I would not fully understand it. It might have something to do with expansion performed/not performed in [ and ].

This is the same problem as in your other question here - your space is 0xC2 0xA0 instead of 0x20. Copy-pasted and stripped from your question:

$ echo "  echo " | hexdump -C
00000000  20 c2 a0 65 63 68 6f 20  0a                       | ..echo .|
00000009
#            ^^ ^^                                            ^^

After deleting and re-typing the two leading spaces:

$ echo "  echo " | hexdump -C
00000000  20 20 65 63 68 6f 20 0a                           |  echo .|
00000008
#            ^^                                               ^

Not sure why yours isn't working

Try this

 :>bash --version
GNU bash, version 3.1.17(1)-release (i686-pc-msys)
Copyright (C) 2005 Free Software Foundation, Inc.


[ $( wc -l < /var/www/some.log  ) -le 6 ] || echo no
no

I hope this helps.

P.S. as you appear to be a new user, if you get an answer that helps you please remember to mark it as accepted, and/or give it a + (or -) as a useful answer.