Fail to self-update composer?

Question

I've been using composer for about a month now. And then one day composer shows me this message:

Warning: This development build of composer is over 30 days old. It is recommended to update it by running "/usr/local/bin/composer self-update" to get the latest version.

I've installed composer globally as per the documentation.

which composer
/usr/local/bin/composer

Running sudo composer self-update gives me this message:

/usr/bin/env: php: No such file or directory

I've checked /usr/bin/env with this command:

whereis /usr/bin/env
env: /usr/bin/env /usr/bin/X11/env /usr/share/man/man1/env.1.gz

my php version:

PHP 5.5.1 (cli) (built: Jul 26 2013 19:50:47) 
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2013 Zend Technologies
    with Xdebug v2.2.3, Copyright (c) 2002-2013, by Derick Rethans

It seems like /usr/bin/env in fact exists.

I'm using ubuntu 12.04LTS.

Update

strace sudo composer self-update 2>&1 | grep open

open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
open("/lib/i386-linux-gnu/libutil.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/lib/i386-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib/i386-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
open("/usr/share/locale/en_PH/LC_MESSAGES/sudo.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/sudo.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_PH/LC_MESSAGES/sudo.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en/LC_MESSAGES/sudo.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/var/run/utmp", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3

Btw, i'm using xampp installed at /opt and php is in my PATH.

echo $PATH

/home/chanhxc/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/chanhxc/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/opt/lampp/bin:/home/chanhxc/pear/bin:/home/chanhxc/.composer/vendor/bin:/opt/lampp/bin

Answer 1

The error message:

/usr/bin/env: php: No such file or directory

tells you that php is not found, i.e. php-cli is not installed or php command is not in your PATH environment variable.

So you need to install (sudo apt-get install php5-cli) or put it in you PATH:

vim ~/.bashrc

PATH=$PATH:/path/to/php-cli/bin
export PATH

UPDATE

Accordingly to Composer with XAMPP for Linux issue symlinking php executable should solve your problem:

ln -s /opt/lampp/bin/php /usr/local/bin/php

Answer 2

this solution will work if you have xampp

ln -s /opt/lampp/bin/php /usr/local/bin/php