ENV is a hash-like accessor for environment variables.

Methods
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Class Public methods
ENV[name] → value

Retrieves the value for environment variable name as a String. Returns nil if the named variable does not exist.

Source: show 

static VALUE
rb_f_getenv(VALUE obj, VALUE name)
{
    const char *nam, *env;

    nam = env_name(name);
    env = getenv(nam);
    if (env) {
        if (ENVMATCH(nam, PATH_ENV) && !env_path_tainted(env)) {
            return env_path_str_new(env);
        }
        return env_str_new2(env);
    }
    return Qnil;
}
ENV[name] = value

Sets the environment variable name to value. If the value given is nil the environment variable is deleted. name must be a string.

Source: show 

static VALUE
env_aset(VALUE obj, VALUE nm, VALUE val)
{
    char *name, *value;

    if (NIL_P(val)) {
        env_delete(obj, nm);
        return Qnil;
    }
    SafeStringValue(nm);
    SafeStringValue(val);
    /* nm can be modified in `val.to_str`, don't get `name` before
     * check for `val` */
    get_env_ptr(name, nm);
    get_env_ptr(value, val);

    ruby_setenv(name, value);
    if (ENVMATCH(name, PATH_ENV)) {
        RB_GC_GUARD(nm);
        if (OBJ_TAINTED(val)) {
            /* already tainted, no check */
            path_tainted = 1;
            return val;
        }
        else {
            path_tainted_p(value);
        }
    }
    return val;
}
ENV.assoc(name) → Array or nil

Returns an Array of the name and value of the environment variable with name or nil if the name cannot be found.

Source: show 

static VALUE
env_assoc(VALUE env, VALUE key)
{
    const char *s, *e;

    s = env_name(key);
    e = getenv(s);
    if (e) return rb_assoc_new(key, rb_tainted_str_new2(e));
    return Qnil;
}
ENV.clear

Removes every environment variable.

Source: show 

VALUE
rb_env_clear(void)
{
    VALUE keys;
    long i;

    keys = env_keys();
    for (i=0; i<RARRAY_LEN(keys); i++) {
        VALUE val = rb_f_getenv(Qnil, RARRAY_AREF(keys, i));
        if (!NIL_P(val)) {
            env_delete(Qnil, RARRAY_AREF(keys, i));
        }
    }
    RB_GC_GUARD(keys);
    return envtbl;
}
ENV.delete(name) → value
ENV.delete(name) { |name| } → value

Deletes the environment variable with name and returns the value of the variable. If a block is given it will be called when the named environment does not exist.

Source: show 

static VALUE
env_delete_m(VALUE obj, VALUE name)
{
    VALUE val;

    val = env_delete(obj, name);
    if (NIL_P(val) && rb_block_given_p()) rb_yield(name);
    return val;
}
ENV.delete_if { |name, value| } → Hash
ENV.delete_if → Enumerator

Deletes every environment variable for which the block evaluates to true.

If no block is given an enumerator is returned instead.

Source: show 

static VALUE
env_delete_if(VALUE ehash)
{
    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    env_reject_bang(ehash);
    return envtbl;
}
ENV.each { |name, value| } → Hash
ENV.each → Enumerator
ENV.each_pair { |name, value| } → Hash
ENV.each_pair → Enumerator

Yields each environment variable name and value.

If no block is given an Enumerator is returned.

Source: show 

static VALUE
env_each_pair(VALUE ehash)
{
    char **env;
    VALUE ary;
    long i;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);

    ary = rb_ary_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_ary_push(ary, env_str_new(*env, s-*env));
            rb_ary_push(ary, env_str_new2(s+1));
        }
        env++;
    }
    FREE_ENVIRON(environ);

    if (rb_block_arity() > 1) {
        for (i=0; i<RARRAY_LEN(ary); i+=2) {
            rb_yield_values(2, RARRAY_AREF(ary, i), RARRAY_AREF(ary, i+1));
        }
    }
    else {
        for (i=0; i<RARRAY_LEN(ary); i+=2) {
            rb_yield(rb_assoc_new(RARRAY_AREF(ary, i), RARRAY_AREF(ary, i+1)));
        }
    }
    return ehash;
}
ENV.each_key { |name| } → Hash
ENV.each_key → Enumerator

Yields each environment variable name.

An Enumerator is returned if no block is given.

Source: show 

static VALUE
env_each_key(VALUE ehash)
{
    VALUE keys;
    long i;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    keys = env_keys();
    for (i=0; i<RARRAY_LEN(keys); i++) {
        rb_yield(RARRAY_AREF(keys, i));
    }
    return ehash;
}
ENV.each_pair { |name, value| } → Hash
ENV.each_pair → Enumerator

Yields each environment variable name and value.

If no block is given an Enumerator is returned.

Source: show 

static VALUE
env_each_pair(VALUE ehash)
{
    char **env;
    VALUE ary;
    long i;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);

    ary = rb_ary_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_ary_push(ary, env_str_new(*env, s-*env));
            rb_ary_push(ary, env_str_new2(s+1));
        }
        env++;
    }
    FREE_ENVIRON(environ);

    if (rb_block_arity() > 1) {
        for (i=0; i<RARRAY_LEN(ary); i+=2) {
            rb_yield_values(2, RARRAY_AREF(ary, i), RARRAY_AREF(ary, i+1));
        }
    }
    else {
        for (i=0; i<RARRAY_LEN(ary); i+=2) {
            rb_yield(rb_assoc_new(RARRAY_AREF(ary, i), RARRAY_AREF(ary, i+1)));
        }
    }
    return ehash;
}
ENV.each_value { |value| } → Hash
ENV.each_value → Enumerator

Yields each environment variable value.

An Enumerator is returned if no block was given.

Source: show 

static VALUE
env_each_value(VALUE ehash)
{
    VALUE values;
    long i;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    values = env_values();
    for (i=0; i<RARRAY_LEN(values); i++) {
        rb_yield(RARRAY_AREF(values, i));
    }
    return ehash;
}
ENV.empty? → true or false

Returns true when there are no environment variables

Source: show 

static VALUE
env_empty_p(void)
{
    char **env;

    env = GET_ENVIRON(environ);
    if (env[0] == 0) {
        FREE_ENVIRON(environ);
        return Qtrue;
    }
    FREE_ENVIRON(environ);
    return Qfalse;
}
ENV.fetch(name) → value
ENV.fetch(name, default) → value
ENV.fetch(name) { |missing_name| ... } → value

Retrieves the environment variable name.

If the given name does not exist and neither default nor a block a provided an IndexError is raised. If a block is given it is called with the missing name to provide a value. If a default value is given it will be returned when no block is given.

Source: show 

static VALUE
env_fetch(int argc, VALUE *argv)
{
    VALUE key;
    long block_given;
    const char *nam, *env;

    rb_check_arity(argc, 1, 2);
    key = argv[0];
    block_given = rb_block_given_p();
    if (block_given && argc == 2) {
        rb_warn("block supersedes default value argument");
    }
    nam = env_name(key);
    env = getenv(nam);
    if (!env) {
        if (block_given) return rb_yield(key);
        if (argc == 1) {
            rb_raise(rb_eKeyError, "key not found: \"%"PRIsVALUE"\"", key);
        }
        return argv[1];
    }
    if (ENVMATCH(nam, PATH_ENV) && !env_path_tainted(env))
        return env_path_str_new(env);
    return env_str_new2(env);
}
ENV.has_key?(name) → true or false

Returns true if there is an environment variable with the given name.

Source: show 

static VALUE
env_has_key(VALUE env, VALUE key)
{
    const char *s;

    s = env_name(key);
    if (getenv(s)) return Qtrue;
    return Qfalse;
}
ENV.has_value?(value) → true or false

Returns true if there is an environment variable with the given value.

Source: show 

static VALUE
env_has_value(VALUE dmy, VALUE obj)
{
    char **env;

    obj = rb_check_string_type(obj);
    if (NIL_P(obj)) return Qnil;
    rb_check_safe_obj(obj);
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s++) {
            long len = strlen(s);
            if (RSTRING_LEN(obj) == len && strncmp(s, RSTRING_PTR(obj), len) == 0) {
                FREE_ENVIRON(environ);
                return Qtrue;
            }
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return Qfalse;
}
ENV.include?(name) → true or false

Returns true if there is an environment variable with the given name.

Source: show 

static VALUE
env_has_key(VALUE env, VALUE key)
{
    const char *s;

    s = env_name(key);
    if (getenv(s)) return Qtrue;
    return Qfalse;
}
ENV.index(value) → key

Deprecated method that is equivalent to ::key

Source: show 

static VALUE
env_index(VALUE dmy, VALUE value)
{
    rb_warn("ENV.index is deprecated; use ENV.key");
    return env_key(dmy, value);
}
ENV.inspect → string

Returns the contents of the environment as a String.

Source: show 

static VALUE
env_inspect(void)
{
    char **env;
    VALUE str, i;

    str = rb_str_buf_new2("{");
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');

        if (env != environ) {
            rb_str_buf_cat2(str, ", ");
        }
        if (s) {
            rb_str_buf_cat2(str, "\"");
            rb_str_buf_cat(str, *env, s-*env);
            rb_str_buf_cat2(str, "\"=>");
            i = rb_inspect(rb_str_new2(s+1));
            rb_str_buf_append(str, i);
        }
        env++;
    }
    FREE_ENVIRON(environ);
    rb_str_buf_cat2(str, "}");
    OBJ_TAINT(str);

    return str;
}
ENV.invert → Hash

Returns a new hash created by using environment variable names as values and values as names.

Source: show 

static VALUE
env_invert(void)
{
    return rb_hash_invert(env_to_hash());
}
ENV.keep_if { |name, value| } → Hash
ENV.keep_if → Enumerator

Deletes every environment variable where the block evaluates to false.

Returns an enumerator if no block was given.

Source: show 

static VALUE
env_keep_if(VALUE ehash)
{
    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    env_select_bang(ehash);
    return envtbl;
}
ENV.key(value) → name

Returns the name of the environment variable with value. If the value is not found nil is returned.

Source: show 

static VALUE
env_key(VALUE dmy, VALUE value)
{
    char **env;
    VALUE str;

    SafeStringValue(value);
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s++) {
            long len = strlen(s);
            if (RSTRING_LEN(value) == len && strncmp(s, RSTRING_PTR(value), len) == 0) {
                str = env_str_new(*env, s-*env-1);
                FREE_ENVIRON(environ);
                return str;
            }
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return Qnil;
}
ENV.key?(name) → true or false

Returns true if there is an environment variable with the given name.

Source: show 

static VALUE
env_has_key(VALUE env, VALUE key)
{
    const char *s;

    s = env_name(key);
    if (getenv(s)) return Qtrue;
    return Qfalse;
}
ENV.keys → Array

Returns every environment variable name in an Array

Source: show 

static VALUE
env_keys(void)
{
    char **env;
    VALUE ary;

    ary = rb_ary_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_ary_push(ary, env_str_new(*env, s-*env));
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return ary;
}
ENV.length

Returns the number of environment variables.

Source: show 

static VALUE
env_size(void)
{
    int i;
    char **env;

    env = GET_ENVIRON(environ);
    for (i=0; env[i]; i++)
        ;
    FREE_ENVIRON(environ);
    return INT2FIX(i);
}
ENV.member?(name) → true or false

Returns true if there is an environment variable with the given name.

Source: show 

static VALUE
env_has_key(VALUE env, VALUE key)
{
    const char *s;

    s = env_name(key);
    if (getenv(s)) return Qtrue;
    return Qfalse;
}
ENV.rassoc(value)

Returns an Array of the name and value of the environment variable with value or nil if the value cannot be found.

Source: show 

static VALUE
env_rassoc(VALUE dmy, VALUE obj)
{
    char **env;

    obj = rb_check_string_type(obj);
    if (NIL_P(obj)) return Qnil;
    rb_check_safe_obj(obj);
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s++) {
            long len = strlen(s);
            if (RSTRING_LEN(obj) == len && strncmp(s, RSTRING_PTR(obj), len) == 0) {
                VALUE result = rb_assoc_new(rb_tainted_str_new(*env, s-*env-1), obj);
                FREE_ENVIRON(environ);
                return result;
            }
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return Qnil;
}
ENV.rehash

Re-hashing the environment variables does nothing. It is provided for compatibility with Hash.

Source: show 

static VALUE
env_none(void)
{
    return Qnil;
}
ENV.reject { |name, value| } → Hash
ENV.reject → Enumerator

Same as ENV#delete_if, but works on (and returns) a copy of the environment.

Source: show 

static VALUE
env_reject(void)
{
    return rb_hash_delete_if(env_to_hash());
}
ENV.reject! { |name, value| } → ENV or nil
ENV.reject! → Enumerator

Equivalent to ENV#delete_if but returns nil if no changes were made.

Returns an Enumerator if no block was given.

Source: show 

static VALUE
env_reject_bang(VALUE ehash)
{
    VALUE keys;
    long i;
    int del = 0;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    keys = env_keys();
    RBASIC_CLEAR_CLASS(keys);
    for (i=0; i<RARRAY_LEN(keys); i++) {
        VALUE val = rb_f_getenv(Qnil, RARRAY_AREF(keys, i));
        if (!NIL_P(val)) {
            if (RTEST(rb_yield_values(2, RARRAY_AREF(keys, i), val))) {
                FL_UNSET(RARRAY_AREF(keys, i), FL_TAINT);
                env_delete(Qnil, RARRAY_AREF(keys, i));
                del++;
            }
        }
    }
    RB_GC_GUARD(keys);
    if (del == 0) return Qnil;
    return envtbl;
}
ENV.replace(hash) → env

Replaces the contents of the environment variables with the contents of hash.

Source: show 

static VALUE
env_replace(VALUE env, VALUE hash)
{
    VALUE keys;
    long i;

    keys = env_keys();
    if (env == hash) return env;
    hash = to_hash(hash);
    rb_hash_foreach(hash, env_replace_i, keys);

    for (i=0; i<RARRAY_LEN(keys); i++) {
        env_delete(env, RARRAY_AREF(keys, i));
    }
    RB_GC_GUARD(keys);
    return env;
}
ENV.select { |name, value| } → Hash
ENV.select → Enumerator

Returns a copy of the environment for entries where the block returns true.

Returns an Enumerator if no block was given.

Source: show 

static VALUE
env_select(VALUE ehash)
{
    VALUE result;
    VALUE keys;
    long i;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    result = rb_hash_new();
    keys = env_keys();
    for (i = 0; i < RARRAY_LEN(keys); ++i) {
        VALUE key = RARRAY_AREF(keys, i);
        VALUE val = rb_f_getenv(Qnil, key);
        if (!NIL_P(val)) {
            if (RTEST(rb_yield_values(2, key, val))) {
                rb_hash_aset(result, key, val);
            }
        }
    }
    RB_GC_GUARD(keys);

    return result;
}
ENV.select! { |name, value| } → ENV or nil
ENV.select! → Enumerator

Equivalent to ENV#keep_if but returns nil if no changes were made.

Source: show 

static VALUE
env_select_bang(VALUE ehash)
{
    VALUE keys;
    long i;
    int del = 0;

    RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
    keys = env_keys();
    RBASIC_CLEAR_CLASS(keys);
    for (i=0; i<RARRAY_LEN(keys); i++) {
        VALUE val = rb_f_getenv(Qnil, RARRAY_AREF(keys, i));
        if (!NIL_P(val)) {
            if (!RTEST(rb_yield_values(2, RARRAY_AREF(keys, i), val))) {
                FL_UNSET(RARRAY_AREF(keys, i), FL_TAINT);
                env_delete(Qnil, RARRAY_AREF(keys, i));
                del++;
            }
        }
    }
    RB_GC_GUARD(keys);
    if (del == 0) return Qnil;
    return envtbl;
}
ENV.shift → Array or nil

Removes an environment variable name-value pair from ENV and returns it as an Array. Returns nil if when the environment is empty.

Source: show 

static VALUE
env_shift(void)
{
    char **env;
    VALUE result = Qnil;

    env = GET_ENVIRON(environ);
    if (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            VALUE key = env_str_new(*env, s-*env);
            VALUE val = env_str_new2(getenv(RSTRING_PTR(key)));
            env_delete(Qnil, key);
            result = rb_assoc_new(key, val);
        }
    }
    FREE_ENVIRON(environ);
    return result;
}
ENV.size

Returns the number of environment variables.

Source: show 

static VALUE
env_size(void)
{
    int i;
    char **env;

    env = GET_ENVIRON(environ);
    for (i=0; env[i]; i++)
        ;
    FREE_ENVIRON(environ);
    return INT2FIX(i);
}
ENV.store(name, value) → value

Sets the environment variable name to value. If the value given is nil the environment variable is deleted. name must be a string.

Source: show 

static VALUE
env_aset(VALUE obj, VALUE nm, VALUE val)
{
    char *name, *value;

    if (NIL_P(val)) {
        env_delete(obj, nm);
        return Qnil;
    }
    SafeStringValue(nm);
    SafeStringValue(val);
    /* nm can be modified in `val.to_str`, don't get `name` before
     * check for `val` */
    get_env_ptr(name, nm);
    get_env_ptr(value, val);

    ruby_setenv(name, value);
    if (ENVMATCH(name, PATH_ENV)) {
        RB_GC_GUARD(nm);
        if (OBJ_TAINTED(val)) {
            /* already tainted, no check */
            path_tainted = 1;
            return val;
        }
        else {
            path_tainted_p(value);
        }
    }
    return val;
}
ENV.to_a → Array

Converts the environment variables into an array of names and value arrays.

ENV.to_a # => [["TERM", "xterm-color"], ["SHELL", "/bin/bash"], ...]

Source: show 

static VALUE
env_to_a(void)
{
    char **env;
    VALUE ary;

    ary = rb_ary_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_ary_push(ary, rb_assoc_new(env_str_new(*env, s-*env),
                                          env_str_new2(s+1)));
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return ary;
}
ENV.to_hash → hash
ENV.to_h → hash

Creates a hash with a copy of the environment variables.

Source: show 

static VALUE
env_to_hash(void)
{
    char **env;
    VALUE hash;

    hash = rb_hash_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_hash_aset(hash, env_str_new(*env, s-*env),
                               env_str_new2(s+1));
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return hash;
}
ENV.to_hash → hash

Creates a hash with a copy of the environment variables.

Source: show 

static VALUE
env_to_hash(void)
{
    char **env;
    VALUE hash;

    hash = rb_hash_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_hash_aset(hash, env_str_new(*env, s-*env),
                               env_str_new2(s+1));
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return hash;
}
ENV.to_s → "ENV"

Returns “ENV”

Source: show 

static VALUE
env_to_s(void)
{
    return rb_usascii_str_new2("ENV");
}
ENV.update(hash) → Hash
ENV.update(hash) { |name, old_value, new_value| } → Hash

Adds the contents of hash to the environment variables. If no block is specified entries with duplicate keys are overwritten, otherwise the value of each duplicate name is determined by calling the block with the key, its value from the environment and its value from the hash.

Source: show 

static VALUE
env_update(VALUE env, VALUE hash)
{
    if (env == hash) return env;
    hash = to_hash(hash);
    rb_hash_foreach(hash, env_update_i, 0);
    return env;
}
ENV.value?(value) → true or false

Returns true if there is an environment variable with the given value.

Source: show 

static VALUE
env_has_value(VALUE dmy, VALUE obj)
{
    char **env;

    obj = rb_check_string_type(obj);
    if (NIL_P(obj)) return Qnil;
    rb_check_safe_obj(obj);
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s++) {
            long len = strlen(s);
            if (RSTRING_LEN(obj) == len && strncmp(s, RSTRING_PTR(obj), len) == 0) {
                FREE_ENVIRON(environ);
                return Qtrue;
            }
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return Qfalse;
}
ENV.values → Array

Returns every environment variable value as an Array

Source: show 

static VALUE
env_values(void)
{
    VALUE ary;
    char **env;

    ary = rb_ary_new();
    env = GET_ENVIRON(environ);
    while (*env) {
        char *s = strchr(*env, '=');
        if (s) {
            rb_ary_push(ary, env_str_new2(s+1));
        }
        env++;
    }
    FREE_ENVIRON(environ);
    return ary;
}
ENV.values_at(name, ...) → Array

Returns an array containing the environment variable values associated with the given names. See also ::select.

Source: show 

static VALUE
env_values_at(int argc, VALUE *argv)
{
    VALUE result;
    long i;

    result = rb_ary_new();
    for (i=0; i<argc; i++) {
        rb_ary_push(result, rb_f_getenv(Qnil, argv[i]));
    }
    return result;
}